He's not trying to talk down to her. He just has a negative score in social skills. Unless they're talking about a few limited topics, like weaponry, the Codex Astartes, and Orks. He could talk about those all day. He's actually trying to be normal but this is the first time in 10,000 years he's been in the same room with mortals who aren't servitors.

It's a little challenging.

But ding ding ding, that is actually a topic he is very interested in, especially considering her smaller stature. "How do you fight a demon? You do not seem...suited to high caliber weaponry." He has guns heavier than you are. Tell him your demon slaying secrets!