Not to toot my own horn, but I think "specialty" is the best option thus far for what we want to convey.
On another note, I want to mention something that I'm not sure if I stated in this discussion, but I know was in the discussion I had at the wiki.
The wiki is, as far as I'm aware, the sole English resource for new fans looking for information on Touhou. If someone starts out like I did and is only passively interested in finding out what it's all about, are they really going to be willing to stumble over something like "ability to the extent of" or "abilities incorporating the capacity to" when it shows up in every single page? Or might that awkwardness be a potential turn-off for someone interested in getting into the fandom, an implication that the people involved in this don't really know what they're doing? It's already awkward enough, in my opinion, that the English wiki has you mouse over Japanese text to get translations for character titles and song names and has Japanese text mounted on the top of the infobox over the English translation of the character's name. I think too many more awkward or unnecessary additions or changes like this are going to be much more detrimental than beneficial.
Personally I'd like to make sure everything in the infobox is a source of quick, simple, and concise information for a new person looking into Touhou. The more streamlined and less confusing or time-consuming we can make everything in that section of each character page, the better, in my opinion.