Rageblade is now on-attack only, not on spell cast nor on-hit. Things like hurricane or Twitch's ult don't let you get more stacks, and you have the stack the moment you auto attack, before you hit.
However, Ezreal's Q apparently counts as an auto attack on cast, so he can get to and maintain 8 stacks outside of combat, just by spamming his q every 5 seconds. I imagine yasuo can do this as well, but no one else can.
54 AD, 72 ap, 64% AS, and 35 to 100 on-hit AoE damage (which his Q applies, of course) is nothing to sneeze at for only 2500 gold.
It's quite the item for both AP and AD ez.