[Selfish Gene]

Spoops, if you took the time to read my first response, you would have read that I'm one of said "few summoners" that you speak of. One of my characters is a dedicated Bonder and the reason I'm sharing many opinions in regards to this is because I know full well of what they're capable of. Also, here's the problem with all of the skills you listed, none of them have scalings. The main difference between those skills and Fast Offense is that it does scale, in the description it even states it gains 1+Rank momentum. Since white spirits increase the rank by one, it literally makes sense as to why it does do something. Let's see the issue with that regarding some skills you've mentioned:

Cleanse Body: Each rank gives a new status it can cleanse, therefore adding another rank doesn't work since it doesn't scale.
Pocket Sand: It doesn't increase the duration of the blind or anything with more levels, it just lets you inflict them with blind.
Watchful Eye: Yet another ability that doesn't scale off of rank because it lets you use the ability with a pre-determined cost and range.
Charge Mind: No scaling, it just lets you use it to amplify your next spell by 2.5x with a pre-determined cost.
Backflip: Max rank is already 0 FP, therefore if you tried to get another white spirit for it, it would refund you FP which doesn't make sense.
Winter's Bite: Yes, in the description it even says 1+Rank duration, but once again it doesn't have scaling properties. It just outright nulls out things that can resist, absorb, reflect ice.

Notice the trend with those skills? No scalings, therefore unless Dev took the time to make white spirit exclusive benefits it wouldn't make sense regardless. For Fast Offense, however, yes, it does make sense. And the issue with your fix is that it goes against the very description of Fast Offense itself. *motions to italicized text*

The mentioned fixes aren't anything horrible for Bonders either, it's literally people saying:

Oh hey, why doesn't Fast Offense just work for 1 Youkai before needing to be re-cast? and Why not limit it to Bonded Youkai instead of every Youkai?

None of these are crippling and will render summoners useless, which is coming from one of the very few summoners there are in the game. I appreciate you taking the time to debate this, though. As I've said, it's great to be able to spark conversation with this.