Honestly, this may seem silly, but how in the forget did Gamzee get the Warhammer of Zillyhoo?
He might have inherited from his ancestor, the Highblood, because he was a general or some stuffe.
And through timetravel and alternate dimensions the hammer eventually ends up shrunken, along with Eridan's rifle, the Quills of Echidna and the Royal Deringer (the sword jack used to slice the ring finger off of the black queen's hand) in the possession of a partially-knit cyborg-bunny on a planet made entirely out of black and white checkered squares, castles and other chess-based shenanigans.
Is that silly enough.