You are limited to one of each upgrade, since the store only keeps one cipher in stock of each type.
Aside from nukes, I don't think your going to be able to use the damage cap up portion on your auto attacks with your single modifier grid.
Replace the Yuel/Percival weapons and the Colossus carbine with Colossus canes, get them to SL10 (aim for 10 canes), you would want to prioritize skilling these weapons up (and the ancient ecke sachs).
See if you can farm the Rose Queen fire staff, if you had any of the fire event SSRs MLBed, then you would just use that instead. Use this EX weapon as a grid filler if you are mainhanding that Ifrit EX Axe.
If you have a water team and can unlock the HP skill for the RotB Katana, I would replace one of the canes for it.
Ignore your Agni and TE until you have a 0* SL10 fire grid, Agni isn't going to be relevant until you uncap his 3rd star. TE is just terrible for a starting fire player to throw their berries into, since the SSR weapon drop rate on it is low, since you're trying to get fodder for your weapons along the way.
I forgot to add, pretend the weapons in the image are 0* weapons.
The canes in that link aren't FLBed, they are 3*ed, and are losing out on 15%(30%) Modifier.