Lovely little bug I've run across. When leaving stores and casinos that make my companions and I check our weapons, and weapons I've equipped to my companions disappears and isn't given back. Arcade lost his Multiplas at the Tops, and Cass lost Dinner Bell. It's that outright pissed me off.

Any way to get these back, or do I need to console them back in?

You'll need to use the console, this is a pretty common (and annoying) glitch

When it happened to me it was also happened with Cass, but it was at the Ultra Luxe. The really annoying thing is that I left Cass outside with all of my non holdout weapons and she still managed to lose them all. I lost Oh Baby, a fully upgraded Holorifle and her Brush Gun. I used the console to put them back in my inventory, it is the only way I know of to get them back.

i think this happened to me with veronica with a 10mm pistol. an now she uses it for ranged attacks although she doesn't have one in her inventory, and after she gets all sort of ranged weapons, from me, to use

weapons also get lost on yourself as well, so i generally strip my companions and myself of them and store the weapons, i only keep holdouts on myself.