Quote Originally Posted by ZeroZet View Post
1 copy + three spirits to power level unit to Awakening as upgrading goes is one true way (for spenders)
2 copies + 2 spirits if you are cheap, but that way a loss of too much potential exp lies.
Worth noting that female platinum units of the same class provide less than 1000 xp, making them less efficient uses of spirits than platinum armours. Personally, I tend to find platinum and black spirits to be the choking point for leveling units rather than the platinum armours, so prefer to save them for use with armours or during events that boost xp gain enough to make other units more efficient (though such events always exclude event units from providing boosted xp).