Sword of Elpisia

Should come naturally if you're already going for 100% completion however to speed up the process when in battle press LB to increase how fast the attack animations play (Max speed is 3x). The fastest way to get into fights quickly is to use the attraction tubes - introduced early on in the game at Alke Pit to spawn 3 consecutive battles and farm them over and over again (power leveling in the process).

At higher levels, later on in the game this can also be paired with a weapon/spread bangle combination which is able to attack all (and kill all) enemies in one attack. Speeding up the process even further.