[Shujin]

Well it´s still kinda weak compared to the other buff skills in the game then cause it can still be hard countered by the mentioned skills and be rendered pretty much useless. Which is given that it´s ice a common strategy to begin with, so the enemy doesn´t even have to adjust.
So having a slight boost in Ice atk, on similiar level like Kraken without the stat buffs and Ice impact, on the ice class isn´t going to make it overbearing. It´s like +13 damage tops(before reductions), with ice skills. Slightly more when you go the Verglas/evoker route.

This way it actually benefits more than just one build. Or more than one gimmick.