[SolAndLuna]

I'm not 100% certain if this is a bug or not, but based on everything else, it seems unintentional, at least.

This is a fairly simple bug, to be honest - The Spirit Jar's Stored Spirit effect wears off if you're brought to 0 HP in any fight, including spars. Normally I wouldn't consider it a bug by itself, it does exactly what it says in the description, but the Spiritualism trait also says that you lose spirits when brought down to 0 HP and those still remain after a spar.

Steps to reproduce:

1. Equip a Spirit Jar (upgraded to at least UL 1)
   
2. Defeat at least 1 enemy
   
3. Get into a spar and get brought down to 0 HP.
   

This doesn't seem intentional, at the very least. If it is, I would like to argue for it to be changed just the same - it feels rather inconsistent, and it makes it rather difficult to use outside of PvE once in a while.