Simply put the only potential use for this set is in pvp with a frostmage build, in pve it is FAR outperformed by...well everything, monster set or otherwise.
My proposed change to the set:
1 part: spell penetration
2 part: 10% chance when dealing damage to surround yourself with a swirling torrent of snow, granting minor evasion for the duration and dealing X frost damage per second for 6 seconds in a 10m radius around the player, minor evasion grants 10% dodge chance. 6 sec cooldown.
Velidreth has 20% chance on all damage, stam builds have easy access to major evasion, people who run frost builds (not many I admit) could use an extra chance to proc winterborn, and last ut not least:
Currently stam has kragh (physical penetration), magicka.......doesn't.
Thoughts?