For a fleeting moment, Domhnall fancied himself an Oracle.
He could see the future.
Guorthigirn was going to die.
The Giant King clapped his hands together, the force creating a blast that nearly toppled Domhnall to the ground.
It was some kind of spatial magic. Guorthigirn reached into a mysterious crack-- a rip in the fabric of matter or space...
From it, he produced a weapon befitting his size: a massive, two-handed warhammer... a Giant Warhammer.
Why?
No-- that was a foolish question.
A proper weapon was appropriate to wield in order to confront a powerful enemy.
A better question was: why in the seVeN HELLS did Guorthigirn not summon his weapon earlier?
It was common sense-- if a trained combatant used some kind of weapon, that granted them... a greater reach... a greater threat level...