Rageblade wins games by itself, and that's overpowered.

I don't remember ever feeling like an item can be the sole reason you win or lose a game in season 5, you know, when this game was balanced. I have had multiple games where it feels like you literally lose 100% because the other team had more rageblades. My last game exemplifies that perfectly. Our team started out the game 12/1 in the laning phase. I ended up 16/2/3 after a couple of teamfights. We had 3 towers and a drag to their 1 tower and 0 drags. Then 3 of them finished rageblade at the same time. Kayle, Kog Maw, and Irelia. We instantly lost the teamfights we had been winning 5 to 2, 2 to 5. 19/3 as darius now, I couldn't 1v1 the irelia who I beat 4/0 in lane after she finished rageblade, or the 5/3 kayle who just finished rageblade, and I could barely get into range of Kog because of his slow.

Now I am no expect in game design, nor a high elo player, but I think we can agree that when you lose a game because of 1 item in the game after dominating and playing as well as possible, its pretty unbalanced.