Be A Diva
You are essentially looking for some way to handicap your pure-kill potential, and you're looking for some way to act that will generate that. There are an unlimited number of ways to do this, here are some that are famous and/or have worked for me:
- Lazy Hercules Syndrome: I once rolled up a 2e character that was hell on wheels compared to the others in my party (19 STR gladiator). So one of the things I did was inspired by one of the Hercules movies I saw on MST3K, where Hercules is always lazing about - Antaeus stopped his wagon where he was snoozing in the back, hassled his wife and friend, but he wouldn't rouse himself to fight the guy until he came around the back and started directly messing with him. D&D combats often don't last that many rounds, and simply not being in the initial rush to contact is a decent handicap.
- Weapon Master Wants A Challenge Syndrome: You've seen this in many forms. Inigo Montoya fighting with his left hand in The Princess Bride. Top samurai swordsman Miyamoto Musashi choosing to fight with a wooden sword because he was kicking everyone's ass too much with a metal one. Derived from that, Ruroni Kenshin's backwards sword. With that same character since he was a gladiator, once he killed someone with a weapon in a fight he left the weapon in them and went to another weapon, going from larger to smaller down to cesti and head-butts.
