The Whispering Ice's Icestorm Crashes Game on Weapon Set Assignment

Steps to reproduce:

1. Place The Whispering Ice Staff in weapon set 1.
2. If the Icestorm skill is not available to be bound to a key, open the skills panel, click the arrow to expand Icestorm's info, and assign it to weapon set 1.
3. Assign Icestorm a key.
4. Enter a map.
5. Notice the Icestorm skill is unbound and is not available to be bound to a key.
6. Open the skills panel and click the arrow to expand Icestorm's info.
7. Game crashes.