UPDATE:

I know this is an old thread but for those who were wondering......

Whether you pick Valkyrie or Devil you get the same reward:
-Lolipop (reduces the enemies matk to 1 for 5 rounds)
-1% exp bolus

The only part that's different is the beginning dialogue depending on which of the two you chose. I found the Devil one a lil funny but the Valkyrie one was amusing too.
Either option you will have to fight Huggen.
He is a fire with hf and has between 10-19k (can't remember). Not difficult

Hope this helps anyone :)