As of card set 1.20 this is the only legendary weapon that isn't a relic.
What Does Deepforged Plate Do?
This is a weapon card, meaning that it is an attachment to be added to a unit already on the battlefield.
Don't be confused by the fact that the plate in question is a suit of armour: this is a very powerful weapon. The wielder (wearer?) gains an additional 5 health and 5 attack power. The unit also gains Overwhelm and Endurance skills, making it something of a super soldier.
This page written for Eternal version 1.20, Card Set 1
Last updated: 11-06-2017