This has happened 3 times now, the last two times I managed to reload and it just happened again. We are walking along, and we get into a battle and then I notice my companions weapon has dissapeared! Now, they did not drop it, and all our weapons are in perfect or near perfect condition so it did not break. It just dissapears! This has happened once to my charecter, once to Gar, and now it just happened to Virgil, and a lot of these swords are irreplacable! How do I stop it from doing this?
Are you certain they didn't drop them? I seem to remember them occasionally flying off when someone would drop them instead of landing right next to them. Are you patched?
Its possible that the weapons are being destroyed in critical failures. Also sometimes when you drop a weapon some one else may pick it up and not equip it. Though, I think i have had the same problem.
And this may seem obvious but it got me a time or two. When you look through your followers' inventories, be sure to check their equiped weapon. I have had followers pick up a weapon I dropped then equip it, and I didn't even think about checkin that when I was goin through their inventories.