"I may not be able to see as well in the dark, but my ears still work." Bert tries not to pout too hard in Karkat's direction but really, this is taking away from his revenge.

"And as for you... mayhap I'll leave you a bit of hair, just around the sides."

He pulls out his unicorn knife and makes sure to move it enough that Sherlock can catch what little light there is to be had reflecting off the blade. Then he leans in and carefully runs it over his scalp, close but not shave close since he can't really see what he's doing in this light.