I was going to report this, but I'm glad other players have noticed. The items transferred are all orange border inventory items. As another person said, the staff of the crones is an orange border item, all alchemy and supply pouches are orange border items,etc. It's like when you dismiss Shadowheart, the orange-border artefact goes to Tav immediately. I also wanted to add that packs, keychains and pouches get transferred to Tav even if they're empty.