Why not just delete Lethality entirely?

Lethality (the stat itself) is literally a nerfed version of flat armor penetration, though. Just reverting it back to normal flat armor pen without any other changes would completely break everything.

The only fixes it needs are to make Ghostblade a bit more expensive and to delete Edge of Night from the game.

Being too readily accessible is Lethality's only problem compared to flat Armor Pen.

Honestly agreed.

just make it a stat that only certain champions can use, think what happens when someone like builds , the mana is a wasted stat.

In the case of Assassins, yes the ROLE, Lethality would be only for them; Juggernauts, ADCs, bruisers, and everyone else would see it as a dead stat much in the way Kennen sees mana as a wasted stat.

Make Lethality have a reduced benefit for ranged.

Problem solved.