Slayer Limb doesn't say anything about two handed weapons. I assume this means that two-handed weapons are eligible for it, but that you still need the other hand to steady the weapon or provide extra leverage when you're actually using it in combat? Or does fusing it in place of a hand mean you can just use it as though it were your hand, and keep the other hand free?

There's obviously nothing in the rules, so by RAW, I surmise that it would work as it is stated in the books - so you're able to fuse with it, but you still have to two-hand it.

As the image of this is awkward as hell, as a GM, I'd make the call that yes, you can fuse with it, and yes you can use it one-handed (and no-longer two-handed), but it gains the Unbalanced Special Quality, or Unwieldy if it already has that - if it already has Unwieldy, I'd give a -10 to Hit for every 5kg it weighs, reduced by 10 for every point of Unnatural Strength.

Or something to that effect.

But by RAW, I see nothing stopping you from fusing a 2h weapon to yourself and then continue to 2-hand it.

Alternatively, if the two-handed weapon is a Basic ranged weapon, you might allow them include a recoil glove (Common avail.) in the maelstrom of flesh and metal their limb has become, thus allowing them to use the fused weapon one-handed without penalty.

It's easier to just disallow 2h weapons from being eligible for slayer limb, instead of creating a bunch of exception house rules for the different cases that exists (not to mention how awkward it would be from a purely visual perspective).

Ah, I want to stress that for my post, I was only referring to 2h melee weapons. Probably should've mentioned that. I'd say that all Basic-class weapons would be fused without question. It's an easy limitation to get rid off, to the point where it'd be weird that fusing something to your arm wouldn't fulfil all the requirements of, for example, a Recoil Glove.

As an interesting RP choice, gifts of the gods can be granted through positive or negative reasons so you could treat this in two ways:

If the gift was taken as part of standard corruption and positive acts of Chaos, allow the user to wield the blade one handed as Chaos sees fit to augment his flesh to allow him to use it.

If the gift was forced upon them as part of a failing and this was the worse of the options the GM could have chosen then they may fuse it with the flesh but not give them the necessary strength to wield it properly. Impose silly penalties and the limb might as well be just a dead weight.

Slayer Limb doesn't say anything about two handed weapons

But it does!

It says any weapon,

Slayer Limb , singular. i.e. one of your limbs fuses with your two-handed weapon.

Now it is physically joined to one of of your arms, but still requires two hands to be used.

I don't see any problems there.

I prefer Calgor Grim's interpretation, as it causes RAW to conform to the whims of the Dark Gods- which, based on the fact that the system is geared towards randomness and whimsy anyway, seems wholly in keeping with the spirit of the game and RAI.

Keffisch's perspective does have the virtue of simplicity and clarity, however.