Are we going to casually ignore the fact that flat arpen got deleted from the game?
Lethality is beyond trash, ghostblade is now one of the worst items in the game, duskblade is only good when paired with 2 other trash lethality items before that its mediocre at best, edge of the night is the only decent one and its because of the spellshield and nothing else.
Building serrated dirk gives you a negative power spike in lane, its literally better damage wise to build 3 long swords or a BF sword than that garbage, and here we arent even talking about lethality runes, that are completely unviable aswell due to not existing in lane thus being 100% worse than flat ad (before arpen runes were an option with strenghts and weaknesses, now its just bad).
Flat arpen fell off late game before, lethality is still not a good stat late game except now its also a bad stat early and mid game, basically its bad all game.
It needs some urgent buffs, how to completely destroy a stat 101, you know theres something wrong when ad casters are going BC > deathsdance every game because there are no other viable pure damage buildpath outside of crit, unless you want to start stacking BF swords.