[Burnsaber]

For the stats, I think they could be higher. 12 at least in def & att. At least in 6th edition the lore suggested that the elves have highly organized military, and even the levies are subject to regular training. When you train regularly for over 300 years, it shows. Also, ap 12 is what the basic human troops have, so it's not that fast. 14 perhaps? or even 16? Mr 12 would be a bit more thematic, they are magical race which nets the +1 advantage but are also descriped as mentally stout and 'willpowerish' race (+1 from that)

About magic. High Elves in the Warhammer lore are the magic users of the millenia, with only perhaps Slann and High Daemons being more powerful. High fire and astral are a no-brainer, but I'd think that they could get access to all elemental paths. Perhaps something like this?

Base F1S3 and 200% F/W/E/A random.

You could also have a loremaster-type unit with diverse randoms on A/E/F/W/S and a "phoenix" high mage who has the concentrated power in astral and fire.

I think that high magic could be represented by a few SXH3 or SXFX spells that are only castable by your best mages. (sure, you can communion and power of the spheres up with indy S1H1 mages, but it'd be more trouble than worth).

About Lothern Sea Guard. Couldn't they be cap only? They could also have higher resource cost to represent the difficulty in mustering them.

As for the two different types of badass cap only h.infantry, it seems pretty... hard to balance so that all of them see use. Especially since both of them would have the "two-handed weapon hard hitter" niche. Perhaps one of them could be a summon?

As for the summons in general, perhaps a dragon* riding lord for a 'tough' (for an elf) thug chassis.

*in order to make to fit to Dom3-verse, you can substitute the word "dragon" for "drake" or "dragoling" or something.