Question: what would Odysseus be feeling if a random crew member or two, instead of Polities, had died in Polyphemus' cave?
He would still be grieving, but I doubt that grief would manifest as a desire to extend mercy. He thought he'd get home without losing a single man and now that chance has been ripped away from him. Desire for revenge would absolutely cloud his mind, but he'd quickly realise the need to protect the rest of his men and pivot towards that.
Polyphemus is blind and no threat, he wouldn't worry about leaving him alive. Then when Athena stops him, instead of saying, "What good would killing do when mercy is a skill more of this world could learn to use? My friend is dead, our foe is blind, the blood we shed, it never dries. Is this what it means to be a warrior of the mind?"
He'd say something like, "You want me to risk more men? Fuck no, I've got to get these people home. What can one little cyclops do?"
And then turn to Polyphemus and go, "Hey, cyclops! I gave you the chance to end this peacefully! You were the one to make things violent! You killed my men! I'm leaving you alive so you can remember them! Remember us! Remember me!" and drop his full address, security number, and computer password as a "watcha gonna do about it champ?" moment.