I more or less agree with Buukki's points, with some additional thoughts.
I tend to default to 5/5 Kendatsuba +1 TP set on anything with significant danger of magical damage. Since Ken+1 head/hands is also not that big of a drop in DPS versus Adhemar +1 head/hands (thanks to all of the acc/crit rate/TA), I'm comfortable with that trade for the added security.
That being said, I'd go for Adhemar +1 head/hands as the priority for a few reasons:
* Perhaps obvious, but if you have sufficient accuracy to not want to swap out Adhemar Bonnet +1 and no big concern about Meva, Adhe+1 head/hands = best DPS. Worth noting that Ken+1 head/hands are no slouch though, lots of Acc/TA/Crit rate is a very nice combo.
* Adhemar is useful for LOTS of jobs. It's still near the top of the pack of TP options for most of the 9 jobs on the set, compared to Ken+1 only being usable by NIN MNK SAM.
* You need two or more HQ abjuration pieces for the set bonus (Crit rate +2% per piece, bonus starting with 2 pieces equipped. Makes HQ Adhemar a bigger step up from NQ than you may be considering.
In case you don't yet have other Kendatsuba+1 pieces, I'd rank the priority as:
1) Body. Best TP piece for most situations on NIN, great Meva. If you play MNK or SAM, equally great for those jobs.
2) Legs. My default TP piece. Samnuha Tights can win in low acc situations, but there's a BIG accuracy gap, so you'll want Ken+1 for serious content. Again, great MNK SAM gear as well.
3) Feet. Yet again, my default TP piece (but Herculean Boots with strong augments are competitive), and also a top notch Shun piece. Good for MNK SAM, yet again.
4) Head. Buukki explained it well, you want the Acc option and it's great for Shun. Great for MNK Acc gear as well, less so for SAM (cuz Flamma+2) unless you need the Meva.
5) Hands. Still good and worth acquiring, just lower priority than the other set pieces. Great Shun and Meva gear, competitive TP piece that may be worth a slight DPS sacrifice from Adhemar+1 depending on your situation.
Note that when prioritizing all of the Su3 and Adhemar stuff, I'd prob slot the Adhemar +1 head/hands combo (and you'd want both since they work well together) pretty high - maybe behind Ken+1 body, but above all of the other Ken+1 pieces.
For Ninja, they are less pertinent for meva than it is for Monk, due to having some protection through shadows.
This isn't
wrong, but from a practical standpoint soooo much of the magic damage you'll encounter is AoE stuff that isn't absorbed by shadows. Leaving MNK and NIN in more or less the same situation, where both get some benefit from Meva.
It's far more common that
physical attacks are the blinkable ones that I can protect with via Utsusemi - stuff that gets through my shadows is far more likely to be magical. That's why personally, I find Meva to be *the* stat I care about for defensive purposes. That's also why I stuck Meva on the Resin slot of my TP Andartia's mantle (paired with frequently used 5/5 Ken+1 TP set, you can stack enough Meva to be very effective).