@Pipio:
I never suggested Arlong was weak, I felt him to be one of luffy's first real challenge fight.
But when it comes to Usopp I would imagine after being on the grand line so long he should have had enough story development to become strong enough to compare to early enemies. Usopp's development so far was incredibly lame. He went from a normal sling shot, to a sling shot with a breath dial on it. Guess what? Its still slower then a bullet. Useful for throwing smoke screens yes, but battling no.
Take for events: Usopp's battle with the numbers was a good battle. From it you would expect him to gain some muscle strength out of it.
Traveling to skypiea: which is a land full of items that can help one do plenty of things. He witnessed how people fight on skypiea with dials etc, but he only left skypiea with a breath dial for his slingshot? He could have easily put a reject or impact dial on his hands to take phyiscal hits and reduce them. Hell even a gas and fire dial like he did with his fight with luffy.
He pulled out great tricks for one fight then stops? huh?
(On a side note, heres some trivia for you. Whats a snipers biggest weak point?… Close combat.)
If Usopp was to develop logically, he would have implemented a way to reduce his weakest point which would be close combat. Also he would improve over all his range of attacks and damage. All his improvements up till this point have been absolutely pointless.
In reference to the bolded, part, he actually built a lot more than breath dials into the Kabuto. He has also used impact dials (fight with Luffy and with Perona, sucking up a bazooka and a giant explosive ghost respectively).