in erc420 vaults each signer has erc20 tokens that represent the signing power.
this way for example if the quorum is 10 and I have 10 tokens, I can sign transactions, but if someone has 9 tokens they need at least one more signer. you could give 1 token to five other signers and none of them can collude to sign transactions on their own, but only one of them is required to help the 9 tokens holder send transactions.