Tiny Crush would be a buckler.
Medium Crush would be a Club, Jo, Mace, Mattock, Morning Star, Nunchaku, and War Hammer.
I felt Small fit best (similar to bola, boomerang, sling, and tonfa)
Half damage is the least it can do. This ensures that there's always a risk when using it - otherwise you can majorly open end, but then choose to only barely knock out your foe. There's never an accidental kill. Using the minimum of half result an open ended result of 220 would still yield a 110 result minimum = death in 6 rounds.