Does block & perry do anything for a Vanquisher using only ranged weapons, no shields?

You can use a pistol and shield as a vanquisher to make use of block, but if you're using two-handed weapons or dual-wielding weapons then you can't block.

Then why does the skill specify "with OR without a shield"? I don't want to be a pain here but it's Sunday and I have nothing to do right now but think about this stuff :)

I just checked on some things and it seems my initial post was incorrect. A shield will add an increased chance to block, but you can block without one if you have passive skills that give you a chance to block (such as "Block and Parry").