What is a good weapon refine for a +Atk/-HP Nephenee (with stock build)?

I have a +Atk/-HP Nephenee (unmerged). What is a good weapon refine choice for her Slaying Edge?

My current situation:

My Nephenee is currently a stock with nothing other than Swap. ie. Special is Moonbow. Giving Fury, Bonfire or something else to her is no issue. But I don't really want to change Wrath nor can I afford anything more rare than Fury. (Among the common A skills, given Wrath, Fury seems a given.) Delivering wrath is what I want her to do. Blow stuffs up in AA with that +10 dmg and -1 cool down every turn. She doesn't need to be used all the time. I'm refining her weapon just for some occasional fun.

Overall, I am at 5k ish score range in AA. So +10 opponents are the norm but for the rarer sword units, +5 ish opponents are also not uncommon. I do have a large barrack. Though I don't have a lot of good blue units that can tank a variety of physical attacks and/or blow stuffs up. (Fjorm and Nowi are off scoring in the first round.) Other than that, I am not sure if there is a potential special role to be filled by Nephenee. (For SI, I have more Nephenee.) But I am happy to be enlightened.