@ManyThingsWe all know GoB isn't perfect, but unlike in Zero Gil isn't directly involved in this war, so he shouldn't be too dangerous. Still, GoB is a storage, but it's finite and what comes out of it must be returned in order to be used again. If Gil doesn't feel like returning something, like in the fight with Gilles de Rais, or loses ownership over the treasure somehow, like with Berserker Lancelot, he can't use it again. It would take time to exhaust his supply though and eventually he might just blast you with Ea.
@Shadow DaedalusIt's cool, I myself had to copy an existing fan made Servant.
Anyways, since he's fitting to be a Caster, he'd have Territory Creation set as class skill. Since he was an inventor and not a mage this skill should be at B and allow him to make a "Workshop". Alternatively, rank A and allow him to make a "Temple" since he built a temple for Apollo, but I don't think it's fitting for him. He wouldn't have High-Speed Divine Words for the same reason despite coming from the Age of Gods, but since he has an ancestor that is a part of Poseidon and received Athena's blessings he should have Divinity at around rank B and Wisdom of Divine Gift around A, maybe even A+, due to his genius. He may also have Innovation because of his inventions and would probably rank EX.
As for his parameters:
Strength: E
Endurance: E
Agility: D~B
Mana: C
Luck: C
NP: EX
One of his NPs would be recreating the Labyrinth like Nero creates the Domus Aurea as an Anti-Army ranking EX. This would entrap anyone around him, including allies, and it should be rigged with traps. I don't think the Minotaur would be included as he's a divine beast that was merely trapped in the maze. For balancing issues it should only be used withing his Workshop and maybe require preparation.
Another NP would relate to his ability to create constructs worthy of the Gods as a Support NP ranking A or A+. This would allow him to make just about anything, maybe even things in the same level of other NPs. With this he could make gear to boost his or his allies' parameters so long as they use them.
And finally he should have a NP that relates to his wings since Athena gave him a pair of his own. These wings would likely not melt in the heat like the ones he made and would boost his agility.