I like it!
If it were a glyph, I could see it being used strategically (e.g. triggering Rogue's Dodge trait). It would lose its effectiveness as a one-time consumable, but it could still have its uses. Personally I'm all for it being a glyph (call it WUUPSIE
Another option is to have it available exclusively in a Beginner/Learner's Mode, but with the penalty of not being able to complete quests or take gold/items out of a dungeon.