Weapon Upgrade Assistance (Destiny 2)

Haven't played for very long. Now I decided to play. All weapons and armor are level 1100. Collected new things and raised it to 1200 level. So, when I try to raise the level of old (from storage) weapons, nothing happens.
The level remains the same and says that the weapon has reached its maximum.
Is there any way to level up old weapons and gear?
There is a bunch of exotics in the store and it's a pity to just throw them away.