Celtic Heroes

???

Are you referring to a melee build? If so, my answer is yes. To health or energy depends on how you play your melee toon. Low focus, high vitality? Health sigils. Low vitality, high focus? Energy sigils.

I personally play a melee build that still casts quite a bit AND relies heavily on an energy shield. My energy sigils allow me to do so and go from mob to mob without the wait. Also, it helps me contribute to boss fights. Without being directly involved with the fight I can stand back and cast support spells to my hearts content, and when energy gets low I just wait 10-15 seconds and I'm full and ready to go again.

They are not required, but they are truly beneficial to have.

Ok Ty Crew

Crew is right on. My mage was built pre-melee so had a bunch of energy sigils so I ended up high on focus and use eshield as well.

But with melee you are less pidgeon-holed. You can go high vit instead if you wish since your elemental damage from melee is not effected by focus. But most of us have other dps skills as well so we tend to go higher on focus.