Umm Hyperion?

Many refer to me as a Giant, even a God. (Myth) - Hyperion is a Titan which is sometimes referred to as a giant

Metal is my Armor, Black is one of my nature. - the lower part is black

I am lethal at close range. - speaks for itself

The holder of the Hearth of a Lion - Not sure, hearth is associated with a place that holds fire...the fire spells Seifer cast at Squall in the beginning?

Can renew dreams, like in the past of ten years - ? His dreams to become sorceress knight is fulfilled?

My look may not reflect my capacities - Looks plainer than Squall's gunblades

Half the name of the god is the clue to my identity - not sure about this

Behold my might in the palm of your hand. (New) - You can hold it