Giant runes are seen as a major advancement from the simplicity of previous runes or the cumbersome issue of magic for arcane runes.
It is legend that the giants ventured to the highest peaks of the world seeking to learn from the Aspects of the world, and up in the cold peaks they learned how to bring their will into reality.
A giants rune is an art, considered to be the highest of callings to even understand runes, much less to scribe them. The giants are always willing to teach their ways to others so long as they will follow their principles, but few manage to stand it long enough to come out true rune knights.
A giants rune seems to not be just some sort of magic the runes themselves distort the world around them to unfold truths unto the world. If a rune were to give life it would bend anything to bring that into reality.