Blue Mage Merit Choices

Even though I'm still not even Lv.99, I've never gone to an event before in the last few years where I've had Chain Affinity ready before my TP. And I spam a lot of magic, too.

And that's the beauty of merits. We can customize how we see fit. You have no use for Diffusion, and would rather maximize your TP with Enchainment. Meanwhile, I do find myself in some situations where Diffusion helps out. Even if it's something as simple as casting a more MP-efficient Refresh on my Fellow NPC when playing around. I find the 1 merit in Diffusion is worth the loss of 10 TP from that last merit in Enchainment.

Merit physical potency 5/5 and get mad after your firsts 10 Heavy Strike casts on Dyna-Bubu DC birds become 10 consecutive misses, i gave up after that so probably you can go higher <.<

Honestly i don't think that 10 macc or 10 acc is going to make or break you, i have 5/5 potency since the 75 cap and didn't even think of changing them, i don't really see myself casting enfeebles on higher content, only mob that gave me problems was Pil with sandspray, and it would have be around the same with 10 macc more for sure. Unfortunately i don't usually get to play blu on VW so i don't have experiences from debuffs on the higher ones.
On the other hand, if i'm casting spells for dmg i'm casting heavy strike for sure, so i guess that the acc helps it a bit on some content.
Those were the reasons from what i choosen to keep the physical merits but i don't think any of the two is a bad option really.
Might as well give it a try to magic acc ones some day, since i have merits to toss anyway <.<