Rather obscure bug with Ethereal Torch : If you swap two monsters holding Ethereal Torch, the torch will sometimes only proc once.
I tested this by swapping a Chip with Replica holding an Ethereal Torch and a Seras with Flanking Maneuvers , given the effects of the torch using Replica.
Sometimes only 20 strength got added, and sometimes 40. The monsters also sometimes stayed in the same place, as intended, but sometimes they swapped. Strangely, this did not seem to correlate with the amount of strength added.
Edit: After further testing with the same setup, the effect rarely activates three times. I have no idea what might cause this.