[Endoperez]

I understood he aims for good items and construction 8, and is going to choose a high-Earth pretender to be able to cast the summons and rituals Construction makes available.

Arcoscephale's Mystics can come close to a rainbow pretender, especially once you hit Constr. 8 and have had time to find all kinds of gems and make some boosters. With Arco, you would already have Earth/Astral access, so Shedu wouldn't be that good. You don't have much Nature, Death or Blood, so any of those might do it... You need powerful beings to wield the weapons; death has some low-level things and better summons, from Black Servants to Bane Lords. I think Nature only has Firbolgs. Blood has many uniques, but you'd also need other paths to get access to them, and you would probably lose the race against human players.

Maybe Earth/Death pretender for Arcoscephale? You might want some Thaumaturgy for early-ish combat support. Even Mind Burn helps a lot. Sailors' Death would is a nice Thaum spell, so Earth/Water could also be interesting. Earth/Air would give you easy access to the Staves of Elemental Mastery. Earth/Fire would be very offensive combination.