Abandoned By A (Potential) Psycho

My boyfriend owns a bayonet. Actually, I'm not sure if it's really his or if he is just borrowing it, but either way it makes me uncomfortable.

He has just left to spend 3 weeks in the army, and as I helped him lug all his army accessories to the train station, I noticed that he was surprisingly heavily armed. Having already discussed the gun in some detail, attention turned to the knife. "That's a very big knife you've got" I said, and had we been other people, or had he not been wearing cammos (which also make me uncomfortable), it might have turned into innuendo or a Crocodile Dundee type conversation ("That's not a knife.."), or maybe even a combination of the two (perhaps with reference to the small size of Swiss Army knives, too, if I had been feeling mean). "Actually, it's a bayonet" he said, and I had visions of him stabbing people visciously, or possibly being stabbed himself. After all, what else does one do with a bayonet? Open letters?

Wikipedia tells me that

"In a modern context, bayonets are known to be particularly good for controlling prisoners, poking an enemy to see whether he is dead and for when the fighter is out of ammunition or so close to the enemy that firing a round is impossible."

Reto is in the Swiss army and so is unlikely to find himself needing to control prisoners, having enemies or fighting anyone (unless it's over the last piece of army-issued chocolate), so really, why does he have a bayonet? And does he keep it in our flat?