Hercules wasn't the only one who heard Arnold's command. All four of them did, he probably wanted to kill the Asgardians by himself which made sense as unlike the Elves, killing the Asgardians might increase his influence quite a bit and he wasn't a big enough fool to waste an opportunity like that.
'Subdue them... that's easier said than done.' A vein bulged out of Hercules' head, 'Killing them would be much better. But since the man has spoken, I'll have to do as asked of me.'
Saying so, Hercules took his gauntlets off as he didn't want to accidentally kill any of them. Heimdall did something similar and put his sword back in the sheath. He was going to fight them with the sheathed sword, that way, he'll be able to kick their asses without worrying about killing them.
