Any ‘Rune #’ that shares the same custom keybind with ‘Offhand Use’ would be rendered unusable.
Example:
Offhand Use: (B)
Rune 3: (B)
Utility Runes: (LB)
Say I’m trying to use utility rune 3 by pressing (LB) and (B) at the same time. Instead of casting the rune as intended, the game would register it as an attempt to do ‘Offhand Use’ (blocking with shield), and overwrite the utility rune list with the offhand’s.
Demonstration: https://www.youtube.com/watch?v=QA5CKtjwNo4
I know that this keybind is not exactly ideal, especially with all the new categories of runes coming up next. But regardless of my custom controls, I still think it would be a good idea for ‘offhand use’ to be temporarily unavailable when already in a rune menu, or at least have this as an option in the game settings.