Would it be at all possible to adjust ambush slash, while you are testing the new khri?

The ambush is fine from a mechanics standpoint, but it uses a hidden break-point inside the appraisal range for 'fair' on slice. If it's above this point, you can ambush slice. If below, it's the same as having 0 slice at all.

Two weapons which both appraise as fair might be able to slash or not, you never know until you physically use the weapon. Even compare doesn't give a definitive answer.

It would make the most sense to me to move it to simply 'fair'.

I've got an email I can share from 2016 I sent to Persida/events about the Ulf'hara keep gladius where this was specifically a problem, but it's always been an issue.