u/Don_Pablo512

I was playing a great N'kari campaign, had the sword on him for over 50 turns. I finally see the Nemesis Crown claimed by Orion so I teleport N'kari there to a nearby cult and proceed to take it and have both. I'm in march getting away from the wood elf swarm coming after me, his army can just reach me and force me to fight. But to my great surprise, their lord all of a sudden has the sword and is using it against me.

Can it be stolen by a hero action or some mechanic I don't know of?? I won this battle and killed the lord, but still didn't get the sword back. It's now in the middle of about 10 wood elf armies as I'm healing up and preparing to go back for it, but I'd like to understand this mechanic. Thx for any insight.