ItsUncertainWho said:

I would not allow this, and many other similar attempts to "improve" or "progress" matters of science and technology.

Mankind has had some 40 000 odd years to tinker and improve upon these combat drugs, and have had uncounted billions of people to do this "work" and they have achieved the standard presented in the books. Now along comes Mr. Assassin, not even a schollar but a mere dabbler in the arts. He spends a few months and a few thousand Thrones (which is NOTHING in terms of resources on an Imperial scale) and he achieves groundbreaking and staggering rates of success?

What wouldn't the Guard give for combat drugs with no downsides? Or any other organisation? It represents knowledge and value on the level of an STC template and is something sector-wide wars would be fought over. It is also completely unlikely that an Assassin could develop this, and breaks game balance.

That's why

Darth Smeg said:

...and also because the Adeptus Mechanicus have a funny habit of turning up and killing everyone involved in research and technological advancement.

That Assassin PC should definitely keep his head down and his mouth shut or it will be "Knock knock", "Who's there?" KAAA-BOOOMMM!!!! "Why it's the Secutor Death Squad come to oppress knowledge you dirty little HERETEK!!!

ZAP! ZAP! ZAP!

If you take Chem-Use and rename it Survival (Heavy Regular Drug Use), you haven't changed anything except the name; it's still a separate skill.

I don't see what the problem is. A typical person who knows how and in what doses to mete our drugs (Chem-Use) does not know why the drugs produce theit effects (Medicae) and does not know what substances are in the drugs (Scholastic Lore (Chymistry)) and does not know how to manufacture them (Trade (Apothecary)). I know how to drink without getting too drunk, but I don't have a clue how to go about fermenting something.

Zakalwe said:

Then there is that

Ah those crazy, eccentric cogboys and their kill-squads.

You know, between the Mechanicus killing anyone suspected of being a Heretek, and the Inquisition killing everyone suspected of being a Heretic, and the Arbites killing everyone suspected of intending to witness something illegal (see the Book of Judgement for some hilariously grimdark crime/punishment examples), it's a wonder anyone gets any work done at all!

Darth Smeg said:

That's what you get when you work for a hyper-radical Inquisitor who's only restrictions were, don't kill any of my people, and I get X amount of any profits.

The balancing factors of these super drugs were cost and time. They were incredibly expensive to make and could only be produced in small quantities. It just worked out that both the assassins in the party were nobles with very deep pockets and a willingness to pay for the best.

From the stand point of an assassin developing this type of thing, I see no problem. If a player is going to invest heavily in a high Int, Medicae, Chem Use, Trade Apoth., Scholastic Lore Chem, all in the +10 to +20 range, why hold them back? Hundreds of thousands of thrones and several years of time, including the help of the Inquisitors personal Medicae and the very radical Tech Priest in residence led to a high value breakthrough that would give a huge edge to one Inquisitor.

ItsUncertainWho said:

I'm normally the first to be decreeing people from creating new technology, or improving their current ones on pain of Adeptus Mechanicus death, but in this case I think it's OK.

Without designing new drugs from the ground up there's a few good reasons to allow it.

The stuff that they dispense to troops in the field is probably in pre loaded syringes dispensed in crates to thousands of troops at once. A few casualties is inevitable and accepted.

Some accurate per person dosing (i.e Chem use), taking into account metabolism existing conditions and approx body surface area is going to go a long way into reducing the side effects (bonuses to toughness tests say).

Instead of getting the standard mass produced combat drugs from the Munitorium, get the privately made in tiny amounts for many times the cost (Trade Apothecary).

Finally get the drugs that counter the side effects without adding their own problems, also very expensive and that's where you really do need a Scholastic Lores to get right.

No Heretek required if you know what you are doing.

in order of appearance,

1, they don't really do the 'same things' in your examples given, chem use is the ability to use the chems, chem lore is your ability to identify what it is and what it does, and chem trade is making it, as hide (i assume you mean hide as concealment is a mechanic) is how well you can blend into your surroundings, and silent move is so you can move up to a point without clanking stomping and farting and thus generally alerting your opposition.

2, i would agree with you on this one, BUT , when the game addresses skill check difficulties it tells the GM to apply these liberally, and mostly generously, IE security for a old rusted lock on a old rotten wooden door vs magstriep/ voice recognition/ eye scanner door which would be +30 and -30 respectively.

3. what would be considered under universal? they divide it up so that your acolytes can specialize in and it adds a dash of "realism" lets make an example,

fred the guardsman recieives training for basic las training, on the battlefield he runs out of ammo for his lasgun so he picks up the closest available weapon, a shotgun, all his years of drilling and training on his lasgun, has prepared him for the world that is las rifles, so when he first pulls the trigger he is knocked on his ass by the recoil of the shotgun, his reloading is sluggish, and he cant aim worth a **** because the weapon is much heavier/awkward to hold.

4. this ones easy, if they are not separate, that means adepts the library nerds of the imperium would become bad-ass snipers,

and assassins would always be running deep into melee,

from what i have read, you seem to want this game to be more like dungeons and dragons, its its own game so please, don't try to turn it into a game that's already out there,