The description of the familiar is:
Formed from the very essence of the caster, a familiar is a precious entity. Weak at first, in time, it can become a potent weapon.
The problem is that when it is summoned, it is generally better than any individual sovereign: 15 HP, 5 ATK, 5 DEF. But it doesn't gain any level. So I don't see how it can became a potent weapon.
