Empower is not worth it, IMO. The stats bonus you get on +1 are not that great. +3 and +4 are significant, but until then, it's better to keep them in Faction guardians. Besides, empower is permanent. 

unless your faction guardian slots are full i wouldnt even consider empowerment. a boost across multiple champions is way better than simply buffing one of them, especially in a faction like the high elves with so many good legos. that said, i'm not sure it would be worth building out your second copy.

I was thinking the same thing so I built her out and put her in my gurading group she's with my two arbitors hopefully I can beat the high elf fw now