Her abilities dont have cast times, her E stuns, so she can freely proc spellblade.Her ult also has 4 casts.
You dont build attackspeed other than runes/trinity really.AS is strong for dueling and the lane phase because her W is really strong levels 4~9.It also heals you while you deal 75 true damage on hit.Only reason you dont build more AS is you dont get to fully take advantage of it in fights since you mostly target squishies and need to burst them.Hitten style is insane tbh levels 5-7-9 and u should look to duel people at those levels ( if u are not behind).
Trinity, titanic, steraks and guardian angel are great on her, you pop squishies with Q-auto-titanic reset auto and the press the attack proc(and ~2 ult casts on the way).
She can stick to people better than most champs especially as she starts maxing her Q.
She can punish lane mistakes with her mobility, burst, great mid game spike and stun.
I'd recommend watching Irelia Carries U and Wickd, as they play her alot.
ICU also makes in depth guides on her.
Shes a fun champ, u get to act differently depending how the environment acts( minions).She also hits her theme better than most champs, just not in a cinematic way, but more of game design way(which,duh, this is a game).
You should also keep in mind that she is getting a rework soon, and riot has a history of removing content from a finished product.
There have been some good reworks, but its really rare and usually is ripping content from other games.
I started ranting and i shouldnt, sorry.Have fun with irelia !