Whether it's 22 determination or 31...not gonna make a huge difference honestly, isn't 9 points of determination like one point and a half of a main damange point xD? (Int,Dex, Mnd or STR). I agree with the above poster, they should really allow for things like 44 crit and 31 det for two reasons:

1 - The relic quest is tedious as hell. Might as well keep people happy after doing them.
2 - It would be less confusing.

If people start slotting materia and after they reach 31 det it says 22 det in their weapons people are gonna be confused (and disappointed, not like it takes a couple hours to do this Novus thing xD). But Donjo totally has a point, Det and piety always appear to have more weigh on equipment than the other stats, so it could perfectly be 22 det instead of 31 (though again, in my humble opinion, that would be confusing
Only time will tell who's right. My money is on 31 DET (have faith guys!)