My Choice of Sch Merit
5/5 Helix acc and att bonus
5/5 Sublimation (Elvaan needs MP badly)
4/5 Focalization (more Macc is always good tho it cost 2charges making it situational)
1/5 Enlightenment (quite handy especially you are a nuker-scholar)
5/5 Stormsurge (7 extra INT + Ice weather bonus, needless to explain...)
This is exactly what I'm doing. 5/5 Helix and Stormsurge are the obvious choices for most, and the rest are up to your personal playstyle. I don't personally have a need for a shorter recast on Light/Dark arts, and when I use Modus Veritas it's usually because I got a half-resisted helix and I want it to not suck so much, so I don't really care to merit it. Also, I tend to sit on Sublimation until its full (plus I'm taru and so my sub isn't that exciting without merits), so 5/5 Sublimation is what I picked.
For tier 2 merits; I originally thought 5/5 Enlightenment would be pretty cool, but then I realized it's not a JA I use too terribly often. Having access to it once every 10 minutes is useful enough for my usual situations, and considering I don't even use it half the time I don't think using all my merits decreasing the timer to 5 minutes is useful to me. So... I've decided to go 4/5 Focalization on the side, even though I'm not sure how potent or useful it'll be, but if it's strong enough to work as a mini-elemental seal (even though it costs 2 charges), it might be worth it. I haven't seen anyone really post on its effectiveness, so I figure I'll just merit it to see for myself since nothing else sounds too exciting.