While sparring today on Skal, against a Weaponmaster today, on my shadowdancer, and I tried to open the fight with Shadow Daze. It hit them, and the sound effect played, alongside the visuals of a successful stun. But the character was completely unaffected by such, and they continued to fight me as normal. I then connected a headbutt from Dirty Fighting which they failed the save for. They also were not stunned for that.
After the bout, some more testing was done, and they failed the saves again, only to be unaffected, even when they were friendly or not. Once we came out of the arena area, however, they worked as per normal. Also, you cannot be rendered unconscious in the Skal arena, so bouts don't technically have an 'end'.