Warlock Spell and Invocation Options

[sandmote]

I feel like having it be an extra 1d6 Force damage would make sense as well.

Force damage wouldn't be bad, but I would rather list a damage type that isn't the same as eldritch blasts'.

That said, I'm still trying to come up with an alternative thematically tied to the warlock putting in extra effort to spill blood. Would acid damage work?