Is it possible via RAW, FAQ, and Errata to have a Legacy Set Heavy Weapon, and Ballistic Mechadendrite? If so would it be able to fire both in a round using Two-Weapon Fighting?

two weapon fighting requires one to use one handed weapons.

Two weapon fighting to ranged is for pistol sized arms.or at least to basic weapon which can be handed in 1 hand.

Guess what a heavy weapon is 2 handed...

Heavy for legacy? maybe as I remember it is not a no way but a legacy is what you usually use for fighting (or always?) thinking in realistic it's a rare thing. Heavy is intended as a support weapon for special situations. opponent got Armour? use a melta. Swarming cultist? It's flaming time...

A Legacy weapon is what you usually use in a fight like rifles or pistols. Heavy as Legacy is probably not the best choice....

Mechadenitre use your reaction action to fire. So Two -weapon fight is not necessary also as you wielding a heavy with 2 hand ..

I think you can fire with it as normal but think about it when using two-handed style you using your arms and your brain simultaneous to hit your target concentrating your fire to it. it is an practiced talent coordinating your two hand.

It is up the to GM whether or not it is allowable. That being said, the Legacy Weapon section on Two-Weapon Wielding via RAW is not against it technically speaking. However it is a very grey area as the section states you require the appropriate two-weapon wielder talent if it is two ranged weapons. Having a ballistic mechanendrite does allow you to fire it as a standard action or as a reaction, but it is technically not wielded in the manner covered by two-weapon wielder.

I would say no. The purpose of the Legacy Weapon set is to have a set of signature weapons that have a level of infamy themselves. A ballistic mechanendrite is an implant primarily and a weapon secondarily. Allowing someone to carry say a Reaper Autocannon or a Multi-Melta legacy weapon and an Inferno Pistol legacy weapon as a set is far too strong. You would basically have a combination that could kill most things from any range.

While it isn't precisely against the rules as per RAW, I would say it is abusing, or at the very least bending, a grey area in the rules, since you are not dual wielding the weapons, but you are still using two weapons. A ballistic Mechanendrite by RAW cannot be used with the Two-Weapon Wielder talent to fire both weapons as it has its own specific rules for its use. But in the end it is up to your GM.

Is it possible via RAW, FAQ, and Errata to have a Legacy Set Heavy Weapon, and Ballistic Mechadendrite? If so would it be able to fire both in a round using Two-Weapon Fighting?

Aren't you supposed to use your reaction to fire the Ballistic Mechadendrite?

Either way, Two-Weapon Fighting disallows Heavy class weapons. That said, you can still fire both in the same turn.

Is it possible via RAW, FAQ, and Errata to have a Legacy Set Heavy Weapon, and Ballistic Mechadendrite? If so would it be able to fire both in a round using Two-Weapon Fighting? [/size]

Either way, Two-Weapon Fighting disallows Heavy class weapons. That said, you can still fire both in the same turn.As far as I know, Two-Weapon Fighting doesn't specifically disallow Heavy-class weapons. It allows for the use of all weapons that can be reasonably wielded with one hand.

I know, it's arguably splitting hairs, but it's a potentially important distinction, since there are situations in which a Heavy-class weapon can possibly be one-handed, depending on interpretation.

well as I see you are able to use the said weapons in the same round but you do not need the 2-weapon fighting only 1 half action to attack and your reaction action...

Heavy for legacy? maybe as I remember it is not a no way but a legacy is what you usually use for fighting (or always?) thinking in realistic it's a rare thing. Heavy is intended as a support weapon for special situations. opponent got Armour? use a melta. Swarming cultist? It's flaming time...

Perhaps I've just played too much Deathwatch, but I'm pretty sure it's perfectly possible to use a Heavy Bolter as an all-purpose weapon. There are basically no circumstances under which a pistol or rifle is *better* than a heavy weapon, unless you count issues like concealability.

Or hand to hand combat when you can use pistols to do quick shots. or when you need your other hand like grapple or hang in things. or the weight of your weapons is bothering. or you need a weapon with faster clip change(switching ammo types) or need some kind of a combi weapon or a 1 shot grenade-launcher or flamer. (which is a possible using basic weapons)

Over all movement is essential in combat . more then fire power in lots of cases....

Bolters is of course a very god all around weapon... I just say using heavy not always practical...