Right -- which is why weapons retention is arguably more important to learn as opposed to gun disarms.
The blog entry I had above, I was talking about some of the Tomiki practices like Tanto Kaeshiwaza waza and Tanto Nage. I don't do this much, but if a student always obsesses about grabbing rather than cutting I'll pull out stuff for them to hold. Gun retention is useful for a small subset. The forests surrounding our university if you don't keep your cell phone, you cannot phone for help. Lose your keys, long way home and you cannot use your car. I'll hand out small whatever's for students to hold on to, sometimes an object to protect and sometimes an object that could be used as a weapon.
Kisshomaru Doshu had written that Aikido practice included Nage with a knife, uke with a knife, and both uke and Nage with knives. I've never seen it.