I have lost a few of my favorite weapons (3 to be exact) due to the horrendous bug that a lot of people have been experiencing. However, I noticed something. I only lost weapons that are in my primary weapon slot. The ones equipped in the secondary weapon spot remained although sometimes I was unable to use them for a few hours but they were still there. I think the item only disappears if it is in the primary weapon slot or is in the salvage matrix when one changes locations via fast travel or joining a pvp or co-op game. So from this point forward my favorite weapons will be equipped in my secondary weapon slot and I will not fast travel or join multiplayer games while I have any weapons in the salvage matrix. And I guess I'll just have to pray that I don't spontaneously get dropped from the Defiance servers while my stuff is in the matrix.

Note: I am on PS3, PSN tag: Katzbalger1