I encountered the warchanter twice and both times my weapons and spells were blocked before I could even select them for use. I believe the card is supposed to allow a wisdom 8 check after I decide to use a weapon or spell. In both instances there was no check and I could not tell if the check was made without me and failed or if they were just automatic failures.

The wording in the app is slightly different than the physical game. If you try to use a weapon or spell, the game will then prompt you to do a wisdom check.