Freed Mana

When someone uses certain type of magic (Arcanes, Healing, Summoning, Totems), he unwittingly frees his mana and open himself to harm. It only takes a single use to be completely vulnerable. This knowledge is not well known and the weapons (called manaric weapons) able to injure those who have freed their mana have been hunted, gathered and destroyed by magic users a long time ago. Yet, some may still exist.

A freed mana will eventually close or heal itself, but the process is not well understood and the length of time it takes can vary.