... Archer is [i]definitely[/i] weaker then Gilgamesh though.

Gilgamesh can use all the Noble Phantasms he wants aside from a few very specific ones at full power. Archer can only get anywhere near full power as a ranged attack that destroys the weapon. Gilgamesh is also only trumped by a few Servants in melee range and he can fire Noble Phantasms like they are coming out of a railgun whenever he wants. He's also not restricted to weaponry and has near-impenetrable armor.

Without UBW, anyone using Archer's abilities is severely restricted, especially if they can't utilize the projectile functions like he can. Tracing is limited strictly to only things that the user can understand by looking at and analyzing them as well.

Archer!Ilya doesn't even have all of the functionalities of canon Archer from what I understand.

Canon Archer, if anything would be broken about him, it would be Unlimited Blade Works. [i]That[/i] is something to be concerned about because fighting him there would be extremely difficult. His usual tactics, though, are dirty tricks and dual-wielding with occasional actual archery thrown in when he gets the chance.

I'll look at the bio in more depth shortly to see if anything actually could be abused, but I'm kind of baffled by the idea that Archer is as broken or moreso than Gilgamesh.