Realistically chainsaws would be terrible weapons as if it hit a snag, such as on metal spikes, the chain could snap at great risk to the wielder.Chainsaws can do pretty gnarly wounds, but they actually are ... pretty bad as a weapon. A sword, an axe, will cleave in a swift motion. A chainsaw is "WRRRRRRRRRRRRRRRRRRRRRRRR", you need prolonged contact. Unless your target is immobile... they just are going to move out of the way.
Think about it - we've had mass stabbings with knives, swords, axe rampage... but chainsaws? Not really.
... but if the group is fine with that, maybe give it the vicious property? (more damage on a crit)