Make valkyries take one or two less spaces in army camps.
Yep, just make her take 7 spaces preferably, though 6 wouldn't make her TOO powerful. Title was able to hold the entire suggestion, so I guess I'll say a little on why.
I know Valkyries have been buffed time after time again - damage being increased, taking less time to train, and utilizing their whirlwind ability further - however, I've found that the Valkyrie is still modest in her use given the cost and utility. I've also noticed she is a very unpopular - being used less than any other troop (except maybe goblins >.< Of course, I may just be mistaken, but I don't think so). They're quite expensive and take a reasonable amount of time to train, but I find that the army camp space being sucked up by them is a bit excessive. Just one less army camp space per Valkyrie would be much more reasonable, in my opinion.