Although the DLC has been out for some time now, I didn't see a thread on this, and I figured I'd post it to inform those who didn't know yet.
 
If you have beat Hardcore mode and thus received the "Hand Cannon", it can be used on Severed. Obviously, it's as overpowered as ever, being able to 1shot an elite brute, but it's fun for breezing through and feeling like Weller the God of Necromorph Dismemberment/Destruction.
 
There also seems to be a graphical bug when Weller uses it, where he shoots at his foot instead of where he's aiming when he fires the secondary "PEW PEW" feature, but it still aims properly. I made sure to contact Visceral/EA about that.

Doesnt it also just use Issacs voice for the pew pew? 

" Doesnt it also just use Issacs voice for the pew pew?  "

I restrained myself from using it during my first playthrough. Then busted it out on the zealot playthrough. Gotta keep that 100% on my Dead Space 2 progress!

This is actually what's making me want to pick up Severed...now if only I had money...

Yeah, the hand cannon made the Zealot achievement for the game and Severed super easy.

This is pretty good news. I did Hardcore as my last playthrough and have yet to use the Hand Cannon. Looks like that's about to change...

I hate the hand cannon and only used it once. I would have preferred a new suit since I only wear the Elite Advance Suit now. Anywho, I haven't purchased Severed (and I will) but I wont use that anymore than I use it now.