When I die, my baubles are totally gone, not dropped on the ground nor present in player's slots.
This happens randomly, not always, so I'm not sure how to reproduce. Checked with NEI's magnet it doesn't fall somewhere out of sight.

FTB Mage Quest pack
Minecraft 1.7.10
Thaumcraft 4.1.2.4

onEquipped is not called on death for me @Azanor

I'll take a look.

Hmmm, do both of you have Cauldron installed?

After spending a few fun minutes killing myself I discovered an interesting issue. The latest forge versions seem to trigger the player death event late every now and again. Most of the time it works fine, but every now and again it triggers after the player has already respawned - as a result the baubles are dropped near where the player spawns, not where he died. It is quite hard to notice since there is also a bit of lag before they become visible and I've found them up to a chunk away from the exact spot the player spawns.

Reproduced here too, running Cauldron(Forge version - 10.2.1231), Thaumcraft 4.2.1.4, Baubles 1.7.10-1.0.1.8

I have bukkit plugin KeepItems for not dropping player's inventories on death, but, obviously it does not know anything about Baubles slots :-)