It's crazy how much people misunderstand Shirou Emiya's Magecraft.
Fanon has really taken over.
Just some corrections to a few things I keep seeing:
He can project Divine Constructs. The only actual limit he has is projecting Ea since it's a weapon for Gilgamesh only. Using them with a true name release is a different story, though.
His projections can last indefinitely and won't vanish even if broken. Gaia plays no part in his Magecraft.
Alteration isn't really in his arsenal. The shape changing thing he does is within the domain of Reinforcement. Alteration is more about enchantment. Like turning a sword into a flaming sword. Simply put, in chemistry terms, physical changes falls under Reinforcement, while chemical changes falls under Alteration.
He's not limited to projecting bladed weaponry. He can project anything he wants as long as he has sufficient understanding of its structure. He just can't store it in UBW.
The rank down of his traced weapons isn't a result of Gaia. It's literally just because there's only so much information he could get from sight alone. The reason why he's able to project a perfect copy of Avalon is because it was inside him for a decade and allowed him to have an innate understanding of it.
The seven steps he uses for tracing only matter when he's still learning to use it. Once he understands UBW, he has no need for it as UBW does it automatically. It's basically just the training wheels.
It doesn't matter what he projects. It all costs the same to pull them out of UBW. It's using them that has different magical energy costs.
I'm pretty sure I haven't mentioned everything, but this is about all that I can remember right now.