The ChainClaw or as Black & Decker call it, the alligator lopper.
Whatever you call it, it's what no Mutant Future style robocrabs should be without. Also if there's ever a Evil Mutant Dead movie I expect "the stranger" to upgrade to one of these.
It's perfect! Things can get away from a chainsaw and while a claw can grab that's about all it does. The ChainClaw grabs'em and saws'em up into to bite sized pieces. Really the only improvement I can think of is if lasers shot out of the alligator's eyes.