Having considered the method of weapons training in DH/RT I'm not a big fan of it. For example, swinging a sword is the same, regardless of whether it is a Power Sword or a primitive one. However to use a hammer is distinctly different: different distribution of weight, handling capabilities and techniques to deal damage.

The same goes with ranged weapons, firing a recoilless lasgun is just as hard as shooting with a recoilless melta gun. When shooting a Solid Projectile weapon though, it takes a different set of skills to maintain accurate fire due to the recoil. Tactile feedback is different too - the weight of the gun changes with each shot as the ammunitiion is depleted, the barrel may warp due to the heated gasses and velocity of the shot.

For this reason I've come up with the following replacement proficiency table. I think it makes more sense. Ultimately I haven't significantly reduced the numebr of proficiencies, just reordered them.

Weapon proficiencies - Melee
Blades : Swords, axes, knives etc
Weapons used to slice, dice and julienne
Melee Weapons Training (Basic /Blade) – single handed
Melee Weapons Training (Long/Blade) – two handed

Bludgeons : Maces, hammers, clubs etc
Weapons that crush, pound and shatter
Melee Weapons Training (Basic /Bludgeon) – single handed
Melee Weapons Training (Long/Bludgeon) – two handed

Mastery : All classes known (also known as ‘Universal’ in Rogue Trader rules)
Melee Weapons Training (Mastery) – All melee weapon types

Exotic : As per standard rules
Xenos weapons, Power Fists, chains or anything else otherwise not readily identifiable
Melee Weapons Training (Exotic)

Notes:
Weilding a single handed melee weapon is distinctly different to weilding a two handed version, thus I've split it up into separate components.
I thought about how an Eldar sword (as an example) might differ from a human one, and beleive that with the exotic materials used etc, the weight would be different enough to require specialised training. It also means that Xeno weapons remain a unique proficiency all for themselves.

Weapon proficiencies - Ranged
Energy : Las, Melta, Plasma
Weapons without recoil
Pistol Weapons Training (Energy)
Basic Weapons Training (Energy)
Heavy Weapons Training (Energy)

Flame : As per standard rules
‘Flamer Template’ weapons
Pistol Weapons Training (Flame)
Basic Weapons Training (Flame)
Heavy Weapons Training (Flame)

Launcher : As per standard rules
Grenade, rocket and missile launchers
Basic Weapons Training (Launcher)
Heavy Weapons Training (Launcher)

Recoil : Bolt, Primitive, SP
Anything with recoil
Pistol Weapons Training (Recoil)
Basic Weapons Training (Recoil)
Heavy Weapons Training (Recoil)

Mastery : Also known as ‘Universal’ in Rogue Trader rules
All classes known
Pistol Weapons Training (Mastery)
Basic Weapons Training (Mastery)
Heavy Weapons Training (Mastery)

Exotic : As per standard rules
Xenos weapons or anything else otherwise not readily identifiable (must be taken per unique weapon)
Exotic Weapons Training (x)

Thoughts?

I like the overall way you are thinking. I felt it was odd how I could wield any primitive weapon with one talent and then turn around and be incompetent with that weapon once a power generator was added to it.

I think this needs one more step added to it. It needs to be transferred from Talents to Skills. Treat them as basic skills (with exotics perhaps as advanced skills) and allow more ane more refined use of them. With Weapon Skill +10 being a certain class of weapons, and Weapon Skill +20 being a specific type of weapon and maybe even allowing Talented (Weapon Skill) be a specific weapon.

So you would have Melee Weapon Training: Long/Blades, Melee Weapon Training: Long/Blades: Swords +10, Melee Weapon Training: Long/Blades Long Sword +20. Or something along those lines.

Plasma weapons wouldn't be recoiless....

I would also give chain weapons distinct classes, as I feel they would need special training and fighting style to use them to maximum efficiency. I do agree that it is odd that power swords are any different to use than "primitive" swords.

This may be a bit of sacrilidge but check out TSR's The Complete Fighter's Handbook for AD&D 2nd Edition for how it broke down Melee Weapons into tight and broad groups.

Some interesting ideas here.

I like the concept of making the things into Skills, but I don't know if I'm comfortable in having characters becoming unbeatable, particularly in the case of Full Auto ranged weapons (ie, always getting maximum hits because of the degrees of success). I will have a look at this though - perhaps it can be mitigated by giving the option to purchase higher levels of proficiency at later career points? I did like the idea of giving +20 (and possibly Talented) to a specific weapon. Nice.

Plasma weapons, I'd need to read up on more. I thought they fired accelerated energy bolts, similar to a melta weapon? Happy to be shown otherwise though - all it would do is move it from the "Energy" to "Recoil" class.

Chain weapons... I can't see that there would be too much difference between a standard axe and a chain axe (they're 'hit and hope weapons). However, a sword vs a chain sword may be divergent enough to differentiate them (a sword generally requires more finesse). I didn't want to bog down the weapon classes like that though. I will have a look at it, and consider the options.

As for the TSR thing, I vaguely remember the idea of the weapon groups, but it's been literally years since I've been down that dark road of awful.

Well, plasma fire bolts of "plasma". As this is actual matter, even if it is highly energised etc, it would have recoil. How much recoil I don't know.

One of the main differences I would see between chain weapons and normal weapons is that to be most effective you would probably want to have some sort of dwell time on the surface you are trying to damage. This would be particularly true against armoured targets... a simple slash with with chain weapon on bare skin or clothes would probably be sufficient, but when trying to tear through carapace armour, or even power armour, you would need a noticable time for it to get through (I am not talking a long time here as they would be utterly useless weapons if that were the case, but enough that I suspect it would lead to a noticable difference in offensive fighting style. Defencively they would be identical to their traditional counterparts).

After these comments I've changed things around a little to relfect the suggestions.

I've moved the Talents into Skills and allowed for (+10) and (+20) increases with generally decreasingly tight groupings. Unfortunately in doing this, the list of skills has blown out enourmously. I'm not too sure I like this, but it's provided for completeness. There would be some decisions to be made by the GM to determine if a specific weapon type belongs to a particular group, but overall these should be straight forward. Peacekeeper_b, I don't actually have the TSR Complete Fighters Book so these may not align to what you see in there.

I also created the melee "Chain weapon" category, and moved ranged Plasma into Recoil territory.

The Ranged weapon Specialisations became problematic, so there's few Specialisations in there. What's the difference between las pistols for example? With Basic weapons it's fine (single shot, semi-auto, full auto) but such options aren't available for many other types of weapons. Perhaps it might work by just listing each weapon type out of the DH rule book (so Lasguns are different to Las-carbines, each SP pistol is a different specialisation etc)? Again, GM effort would be required if we go down to this level of detail.

I was loathe to have the ranged weapons get +20 when on autofire. It would cause maximum hits virtually all the time (+20 specialisation, +20 full auto gives a huge advantage). Something to keep in mind I suppose.

Anyway, here we go:

Weapon proficiencies - Melee
Blades : Swords, axes, knives etc
Weapons used to slice, dice and julienne – does not include chain weapons
Melee Weapon (Blades)
Melee Weapon Advanced (+10)
Weapon groups: Swords, axes, knives etc
Melee Weapon Specialisation (+20)
Weapon groups: One handed swords, one handed axes, knives, two handed swords, two handed axes etc

Bludgeons : Maces, hammers, clubs etc
Weapons that crush, pound and shatter
Melee Weapon (Bludgeon)
Melee Weapon Advanced (+10)
Weapon groups: Maces, hammers, rolling pins etc
Melee Weapon Specialisation (+20)
Weapon groups: One handed maces, one handed hammers, two handed maces, two handed hammers etc

Chain : Swords, axes etc
Weapons that have blades replaced with a chainsaw mechanism
Melee Weapon (Chain)
Melee Weapon Advanced (+10)
Weapon groups: Swords, axes etc
Melee Weapon Specialisation (+20)
Weapon groups: One handed chain swords, one handed chain axes, two handed chain swords, two handed chain axes etc

Exotic : As per standard rules
Xenos weapons, Power Fists, chains or anything else otherwise not readily identifiable
Melee Weapon (Exotic)
Melee Weapon Advanced (Exotic) (+10)

Weapon proficiencies - Ranged
Energy : Las, Melta
Weapons without recoil
Pistol Weapon (Energy)
Pistol Weapon Advanced (Energy) (+10)
Weapon groups: Las, melta
Pistol Weapon Specialisation (Energy) (+20)
Weapon groups: Las, melta

Basic Weapon (Energy)
Basic Weapon Advanced (Energy) (+10)
Weapon groups: Las, melta
Basic Weapon Specialisation (Energy) (+20)
Weapon groups: Las, melta

Heavy Weapon (Energy)
Heavy Weapon Advanced (Energy) (+10)
Weapon groups: Las, melta
Heavy Weapon Specialisation (Energy) (+20)
Weapon groups: Las, melta

Flame : As per standard rules
‘Flamer Template’ weapons
Pistol Weapon (Flame)
Pistol Weapon Advanced (Flame) (+10)
Pistol Weapon Specialisation (Flame) (+20)

Basic Weapon (Flame)
Basic Weapon Advanced (Flame) (+10)
Basic Weapon Specialisation (Flame) (+20)

Heavy Weapon (Flame)
Heavy Weapon Advanced (Flame) (+10)
Heavy Weapon Specialisation (Launcher) (+20)

Launcher : As per standard rules
Grenade, rocket and missile launchers
Basic Weapon (Launcher)
Basic Weapon Advanced (Launcher) (+10)
Basic Weapon Specialisation (Launcher) (+20)

Heavy Weapon (Launcher)
Heavy Weapon Advanced (Launcher) (+10)
Heavy Weapon Specialisation (Launcher) (+20)

Recoil : Bolt, Primitive, SP, Plasma
Anything with recoil
Pistol Weapon (Recoil)
Pistol Weapon Advanced (Recoil) (+10)
Weapon groups: Bolt, Primitive, SP, Plasma
Pistol Weapon Specialisation (Recoil) (+20)
Weapon groups: [As above, plus] Single shot, short burst, autofire

Basic Weapon (Recoil)
Basic Weapon Advanced (Recoil) (+10)
Weapon groups: Bolt, Primitive, SP, Plasma
Basic Weapon Specialisation (Recoil) (+20)
Weapon groups: [As above, plus] Single shot, short burst, autofire

Heavy Weapon (Recoil)
Heavy Weapon Advanced (Recoil) (+10)
Weapon groups: Bolt, Primitive, SP, Plasma
Heavy Weapon Specialisation (Recoil) (+20)
Weapon groups: [As above, plus] Single shot, short burst, autofire

Exotic: As per standard rules
Xenos weapons or anything else otherwise not readily identifiable (must be taken per unique weapon)
Ranged Weapon (Exotic)
Ranged Weapon Advanced (Exotic) (+10)