On the subject of arm wrestling, I am quite weak physically, but in the few seconds from the start to my loss, I feel... I dunno... It's kind of like a cloak? Hard to describe. It starts at my wrestling hand and I feel I have claws; I feel other alterations begin and spread but by then I've lost and the moment has passed.
Also I have excellent night vision; to the point where if there is the tiniest glimmer of light in the room, I can see colour. When my friends are blind, I think: "What the hell? You wimps it's only dusk... oh..." and realize it is actually night time. I still get confused over this at 18.
I have also had to fight the urge for years for the all fours on stairs, and now it is only lack of flexibility that stops me; going up or down with a handrail on either side I can still do it, and usually do before I can stop myself
Whenever I get into a fight; combat seems to be multiplied fourfold - the urge to drop to all fours, the urge to ignore tactics in favour of wild flailing, the urge to revoke technique - all need to be fought in someone of my physical strength. And that is before we take into account the enemy himself. Technique, tactics, speed, and agility are key for me, and the threat of losing it in even my karate sparring scares me for a RL fight; and indeed I have had the crap beaten out of me because of losing control at the wrong time.
Still, on the other hand, momentary lapses have conversely saved my bacon; a strike that I had no chance of blocking dodged because my other self took over, dropped me into a crouch and pounced, or I spot someone creeping up who thought themselves cloaked in darkness.
TL;DR Although not realizing it at the time, my secondary self seems to affect my state of mind in times of stress, and there may be something of an animal's keen eyesight in me. I wouldn't trade it for the world.
P.S. Yes I love writing about combat