Just a semi-random idea I came up with: a lizard who can regenerate limbs had a mutation so instead of just growing a new limb when they are damaged, she grew an extra set of arms during puberty. She decided these were a blessing rather then a curse she started learning various fighting styles that focus more on punches and upper body and started learning how to use all four of her arms.

Still need to come up with a name for her but I kind of like her design...