He's one of the two new summon units (apart from the ones announced). The other is a silver male elf archer.

The soldier has less health, as all elves do, but good attack and defense, as well as 5 resistance. Problematic to mincost because you need to pull him from the shrine, though.

The archer is actually very useful. He has the Excellent Arrow skill, which just so happens to be the same skill Spica has. Yes, this means you can SU her without needing more copies of her!