So far, it seems like Claws, Palms, and Clubs are pretty near the top in multiplayer matches. I might put a bow up there for it's long range/speedy attacks, but I don't have a great bow yet. Ah heck, I'll do a fake tier list and see what people think...
From my opinion, it's:
Top tier:
Claws
Clubs
Palms
High:
Bow
MAYBE Blades
Mid:
Blade
Cannon
Low:
Orbitars
Arms
Bottom:
Staves
This is mostly due to my weapon selection at the moment.. I do have a pretty nice staff, but with a bit of lag and the overall quick movements in this game, sniping is incredibly difficult. Claws are also overused, which make it hard for staff users...
Orbitars and Arms both have potential, but I haven't seen a reason to believe that they're any better than the weapons above them. I'd think Orbs might be higher... maybe top of mid. Not sure.
Palms are so high because of the auto lock-on, fast movement, fast firing, and tons of damage / second. Combine them with a few offensive abilities, like black hole, and they're ridiculous.
Blades are pretty average, on the whole. I've had a couple blades that I really liked, though.
Bow might move to top tier... it seems to be the most effective "overall" weapon in the game. Crazy long range/homing and decent mid/short range for some of them... The only thing keeping them down is that the faster short range weapons seem to overwhelm them pretty easily.
Thoughts?