I personally have not many problems with Darius' design, except...
... for this stupid random heal on Q.
Darius is a scary opponent to face, one who, if you make a mistake will totally crush you with his damage. However, that's how he has always been and that's not an issue: the counterplay to that: trade smart and get every chance of free harrass you can get, so he's too low to engage savely and you can actually CS.
But with this heal this only lane-weakness he had was completly thrown out. "Yeah but don't get hit by Q" - this pretty much means "give up on a shitton of CS, lane pressure and lose lane by default". And to all those who says "ganking him is counterplay too!" well, too bad that applies to every single champion there is. Most champs cannot fight a 1vs2 early in the game, especially when a redbuff is involved. If your only relevant counterplay is "ganks their sorry asses" then that's bad design. That was specifically one of the reasons Yorick was held in a perma-gutted state forever btw.
And on top of that the heal is a total thematic failure. Darius is no magic weapons user. He's no hemomancy user. Heck, he's the character who jumps into a fireball fight with an simple axe AND WINS. THAT'S who Darius is. He uses his axe for one thing: kill people with it. Not to heal himself or do any fancy gimmics. He has an axe and knows how to use it. That's all. And in the chaotic magic mess that is the character cast of this game at times, this is what makes him special.
As for the initial purpose of the heal... I am not sure why one of the most notorious lane-bullies in the game needs a buff on teamfighting. Either your champ excells at one thing ot the other, not at both, that's pretty unfair if you ask me...
