Board Thread:Questions and Answers/@comment-200.43.89.194-20180205151222/@comment-26447088-20180205174427

The armory is just extra space to store your units. If you want to hide units from your Unit List, for whatever reason, or clear out units that you don't use without selling them off, that's the place you put them.

When you reach your unit limit capacity, all pulled units will go to your Gift Box. Any units you get from quests will also be sold off automatically, unless you have Auto Enhance enabled for a unit.