Glass Veil is incredibly exploitable

[Mohl97]

For whatever reason, the cooldown on it is counted as a debuff, meaning roughly two gestures and a blast shower is enough to cancel the cooldown before the invincibility frames run out, resulting in complete and permanent invincibility for the entire run (minus mithrix's last phase). On top of this, it pairs with shaped glass for completely free damage since you already have 1 health to begin with, so you can easily snowball it into wiping the map and being completely unkillable.

[BrandonRosa]

This item was never supposed to be considered balanced but more a fun glass canon item. But from what you're describing it does get absolutely broken. Ill change that