To repair, figure out the lower between
[Weapon rank-10] or [Rank needed to craft weapon-10]
Therefore, rank40 is enough to repair every item currently in-game. The only thing I can think of that would prevent you from doing repairs is if the weapon requires a different skill from the one you've been trying to use. For example, I believe some of the Prime weapons require goldsmith to repair instead of blacksmith.
According to your sig, you have at least armorer, blacksmith and goldsmith at rank50, so really, I don't see why you wouldn't be able to repair most of them.
According to Zam, Ifrit's Battleaxe
, Ifrit's Blade
, Ifrit's Bow
, Ifrit's Cane
, Ifrit's Claws
, Ifrit's Cudgel
and Ifrit's Harpoon
all require goldsmith to fix.
Moogle weapons seem to use blacksmith, leather, goldsmith, and so on, following the usual pattern most weapons normally use.