This mostly covers non-stealth attacks, in the idea of military combat or an arena fighting match. <PERSON> better covers stealth, which would likely be the way all rewinders prefer to fight.
Editted to readdress the OP's question.
The rewinder with the most mental stamina would win every fight. For example, <PERSON> would slash at <PERSON> with a knife, then <PERSON> would rewind in order to block/parry, then <PERSON> would rewind to change his attack. These exchanges would continue until both parties are out of mental stamina. This means that stamina would act like "a shield", meaning you would want to preserve it. After all mental stamina is gone, the combatants would start taking real damage, and possibly be killed or beaten. Because of this, combatants would most likely allow attacks to land before rewinding, to see how lethal they are, and decide whether they want to waste stamina for a little pain or if they really do need their arm back.
This would pose an advantage for poison wielders. If the poison can stop the defender from rewinding all together, than any attack would be a huge benefit.
After the shield/stamina is gone, it is either whoever can endure the most pain and still fight, or who has the most skill.
When exchanging in a gun fight, it would be more difficult to see the threats coming, meaning the rewinders would not be able to rewind before the attack hits them, but rather after. 494
When <PERSON> snipes <PERSON>, she would rewind after there's a bullet in her shoulder, unless she can magically see the bullet. However, in anticipation of being hit, if there is enough distance between the attackers, the defender could rewind as soon as they hear a gun shot. This would potentially save them from being killed or knocked unconscious, so it would be the best move. However, this would lower stamina, making it a risk; if the bullet would have missed, the defender still wasted stamina rewinding. This means whoever fires more bullets would likely win.
In ranged combat, the attacker has the advantage of surprise, because the defender is unable to see the attack and react fast enough. However, in this case both parties are very equal. If a shot is lethal, brain or heart wound, it can either instantly kill the defender or prevent them from rewinding.
Overall melee fights of equal stamina would result in an ordinary knife fight, except there is a bit more strategy with which hits to take and which to avoid. A gun fight would result in both parties spamming their guns, wasting all their stamina, and then it would be a normal gun fight. 516