Well, at least the guy knows where he stands. He finds that both amusing and impressive at once. Not many are willing to pass themselves off as abnormal.

"Oh yeah?" He twirls the handle a bit, almost happy to hear that bit of news. "Well, guess I should be glad. Wouldn't want anyone just snooping about my weaponry, now do I?"

Though if Mamoru wants him to talk about his weapon, he sure wouldn't mind giving him a small summary. You can see it in his body language, he wants you to ask.