Darius has needed some defense buffs ever since spear of shojin. Since then, its been a shitfest toplane, and Darius went from "aggressive lane bully" to "Lord let me make it out of this lane alive so I can be a meatshield in mid-late game". Level 2 junglers have cheesed darius hard, as well as vayne, riven, viktor, karma, kennon, neeko, the list goes on. I would prefer his base armor and mr be buffed, but the heal on q works as well. Damage was fine though, not sure why they buffed it.
Things that needs to be looked into for Darius:
His tooltip for his ult is completely misguiding: it doesn't calculate his bonus AD from his passive, making the damage seem smaller than usual.
His Q's hitbox would preferably be bigger, so divers could stop endlessly going in without repercussion
W's auto attack slow should be back, but not as drastic as it once was. A mild auto attack slow would help against....divers.
Q and W's damage is completely fine. However, his lvl 1 ult damage is laughable. His ult's damage only begins to kick in around level 11, and until then, its more reliable to use his ult as a way to get the 5th stack on the enemy (using the ult as a gapcloser), and finish them off with a Q. Remove the damage buff from his Q, move it to ult level 1 ult.
His E is fine as it is. Long cooldown, but it's reasonable. I would prefer it to have a shorter cooldown to counteract the dashes, but I feel like that would be too oppressive.
I get if some of you guys don't like the idea of Darius getting buffed, but he really needed a way to deal with toplane's bullshit. Before, he was a zoning menace in teamfights, who's healthbar would never go down if the enemy never played around him. Now, he can get bursted down by anyone. I've seen support sonas with lich bane ignore my mr and do 700 damage.
The right thing to do wasn't to buff Darius, but it was to nerf diver's damage output/cooldowns. What a shame Riot keeps inflating damage.