Around Logan's left arm, there was a constant robotic casing. For the most part, this was because he covered up what his Dalki arm looked like. It didn't look too out of place for Logan because his whole suit was made up of strange nanomachinery, which he could break down to create different suits or use for unique circumstances like the current one.
The good thing was, Logan always had a set of supplies with him, and he had somewhat predicted that there would be vampires at the Dalki main base. One of his guesses was that Jim would be here, though he wasn't considering encountering this many.
Still, because of this, he had prepared a special spray with him that allowed him to blend in with other vampires. They would be picking up his special scent, and thus, he also sprayed it on Borden and Layla for safe measure. Subclasses carried a different and detectable scent, and as for Borden, Logan honestly had no idea, but there was no need to take risks.