[Shujin]

Wait, it didn´t before? I thought that was kinda the point of the "Does not trigger ice sheets during the duration when walking on them!" line o.o
Kinda assumed that being pushed counts as it aswell.

Honestly, I am fine with revamping it´s whole effect when you don´t want to give free res. Which is kinda understandable given how powerful a loss of 1 M can be. (Darkshield still has it though)
I don´t think adding frostbite resistance alone will make it much more used, considering it´s wonderfully short duration. Ice Res is a little meh because of all the ways to counter it.

If Ice atk is also a no-no we could just make it like:
Rank 1on´t trigger ice tiles by walking
Rank 2:Celsius immunity
Rank 3:Frostbite immunity

1+rank duration?(Or 3+permafrost)

While not strong it´s still "Protection from winters warth", would be more useful in my eyes even when still compeltly situational.

[Neus]

It protected from Frostbite's effects, but only while the skill was active. IE, if you were inflicted with Frostbite and then the skill ended, you would then be subject to Frostbite damage.