So far I´ve had 2 weapons go missing, first a hammer and than an axe, in both cases I was dual wielding and in both cases it was the main hand weapon that went missing. Both times I went into combat with 2 weapons and than noticed that I was swinging only one weapon at some point during the fight. The first time it happened I wasn't too bothered it wasn't an upgraded weapon and honestly I thought it might be a one off thing. Restarting the game doesn't help, I could load an older save but my last one was 8 hours ago (yes I know, I should save more often) and since this seems to be a recurring thing, I don't want to set myself back 8 hours just to have it happen again, the autosaves are all after I already lost my weapon.