I refine 2** canon, flames, medkit, jap dart and got a Pink AA XD
Dont know if Axe / Spear / Boomerang is possible. GM... correct me if i'm wrong!
All of these are possible, but of course, they're more rare then regular prizes.
Item refining can be pretty awesome.
best thing I got out of them so far were level 4 pearls including a harm level 4.