You're nerfing the wrong part of Irelia, and for the wrong reasons.

You're nerfing Irelia next patch, though in typical Riot fashion, you refuse to acknowledge the actual issue, and nerf around it until the champ is barely a shell of what it was (or remains broken like a lot of braindead clickers lately).

Irelia's issue is not any part of her kit, rather it's the items she likes to build, particularly these two:

She has decent scalings and base damage, so when you add 400+ on-hit damage to that, on top of the empowered auto reset from Titanic... it's no wonder she scales too hard into late game.

It's also not surprising that every champ who likes to build Triforce has been an issue, or is currently an issue.

So nerf Triforce's base damage a LOT, but give it a bonus or total AD ratio. Force her to build damage to do damage (meaning she's not this unkillable assassin monster late game), and at the same time, you'd also eliminate champs like Hecarim, Trundle and Skarner building Triforce into full tank and melting people. You could also nerf Titanic's base damage, though I think nerfing Triforce would be enough to curb both issues.