Darius is getting buffed
10% more damage on his W at all ranks, 5% more armor pen at all ranks of his E.
Darius doesnt need buffs, he has a 10.8% play rate in plat+ with a 49.7% win rate. He is also rocking a 36% ban rate, which means that darius is pick/ban in almost half of all games played in plat+.
Riot is trying to buff him for worlds because crowds love a good ult pentakill, but pro teams dont play darius unless he is ridiculously OP because of how easy he is to kite in team play. Also the armor pen buff is crap because it only is coming from the current trend of darius players to build
over 
upgrade.