Autocrossbow is the most usefull tool of all. It delivers damage to a whole group of enemies, it often rescued me out of seemingly non-win situations. My next favorite is the Chainsaw. It can do a lot of damage and is very good to use it against bosses, cause Edgar (at least in my game) is very fast with it and does good damage in a few turns. The third favorite is the Drill. I think the Drill is a little bit less usefull then the Chainsaw, I don't know why. Maybe because Edgar doesn't look that cool in an outfit with the Drill.

My least favorite (sorry Darken Falken) the Bio Blaster. It is really useless in my opnion, it only does poison and it doesn't look really cool.