Let's be honest here, the rune is a complete mistake and is a result of many horrible, horrible balancing issues.
Sure its weak as hell in the early game but being the fact it infinitely scales and gets stronger just by hitting any champion hit. (Doesnt matter if you preformed an auto or spell)
The Rune is not healthy at all.
Especially when a champion like Karthus can abuse it with his free ranged ult and passive that can let him gain more stacks upon death during team fights.
It only gets worse when champions have poke in lane. They have little to no risk to use it, they will just poke down a champion low enough to proc the rune and deal more damage, the Cool down is not really helping if they happen to get a kill and reset it.
It reminds me of the Feral Flare days in Season 4-5
(I dont remember too much but I know it was removed for a good reason)
The sooner you remove the rune the better for the state of the game.
Besides the Buff to hail of blades is good and deleting Conqueror in the next patch is a good discussion in the long run.