@C0ntr1v3d Yes, you are right that not every relic should react in reverse in particular those that react after being hit as they are not worn by the possessed. The Avenging Energy Staff is a good example. However, the Jakugan Sword is not logical. It may say "After hitting, if target's Life is below 50%, it deals xxx points of Physical Damage to all enemies. 2 uses." and I know what you are saying, but it is a god damn mindless sword that is wielded against a target which is at that point the enemy of the wearer and it should not hit back at the other (my) team, in particular if it's at full health - it defies logic!
And I will pay a bit more attention to all the various stamina drain relics from now on to see how they behave in regards to their description.....
Edit:....looking through all the relics on the wiki only two stamina drain relics should still drain stamina from your team when triggered by a possessed monster: Avenging Energy Staff and Oblation Trap. In theory, the possessed monster should also be counted as 'enemy' at that point.