[Nightblade]

Same with enchanter pets, but what I think you're getting at is the visualization of them holding two weapons, versus actually using both.

I can give my dinky little mage pet two spears or whatnot, but he'll only use one. Why? Because while he looks like he's holding both, there's no dualwield skill to roll a check for, so, only swings with one hand. Until 24, DW-checks for attacks auto-fail for mage pets.

Hope this clarifies it.