I have a traps assassin with 2 claws ( Claw Block )
It's been a while since i've played, I recall putting stats into dex until I hit a certain "Chance to block" percent,

Does anyone know what % I should be getting on a trapsin for pvp?

Dex doesn't change block chance with weapon block. Only skill points change it. 63% chance to block at lvl 42 weapon block is the maximum usable setup.
On a trapper you will likely be looking at 56-59% depending on how much you want to dump into the skill.

Appreciate it.