Stop trying to pump power into darius E passive and W
This kind of shit only encourages the toxic tri force build and further disincentivizes darius players from going cleaver and caring about decimate.
At some point you're just going to have E > AA > W > AA > R become his main combo while q is something he thinks about if the enemy doesn't happen to be in melee range.
Scrap the PBE buffs.
If you're intent on him being better in pro play (With the added bonus of not breaking low elo), then these are the kinds of changes you would make:
E 15 range nerf reverted (back to 550 as it was when darius was released) Decimate missing health heal from 12% at all ranks to 10%/11%/12%/13%/14% Rank 5 decimate unlocks champion healing cap (currently set at 3 champions on live)
I guarantee you those changes above wouldn't be felt even the tiniest bit in the lower elos while giving darius something to look forward to in higher elos while also bringing back much healthier cleaver tank builds that don't force darius into this toxic "I'm going to build to try and just one-shot this motherfucker with my E > AA > W > Q > R combo, and if it doesn't work, I die hard or have enough attack speed to get noxian might anyways"
The early game decimate heal nerf would also make him a little bit more bearable in lane and allow people to feel like they can trade back a little better into him while the darius gets to feel better after decimate is maxed out and if he lands a clutch 4+ man decimate in a teamfight (which isn't as rare as some people think when darius isn't the only frontline in the game, WHICH WAS THE INTENDED WAY TO COMP WITH DARIUS).