3 command seals

Yes. All skills will be usable again regardless of its cooldown before they died.

Though, I think the mystic code's skills might be an exception. Not sure if the MC's skills are reset or if they stay on cooldown.

Servant skills are refreshed. Mystic code skill are not, and if your servant had buffs due to a craft essence like Castle of Snow or Volumen Hydrargyrum those will also not be reset.