The thing is that getting AP and armor pen (essentially AD) is kinda counter productive since her ult doesn't scale with both AD and AP, so getting savvy might not really help you (unless you are going AP, which I don't suggest doing, since you would not be improving bladesurge or hiten style as effectively). Getting strength of spirit may also not help you because she has a pretty low mana pool (you may have runes, idk)
I mainly jungle with her so i go 1/19/10 with smite/ghost as spells.
O: smite mastery
D: armor 3, MR 3, dodge 4, nimbleness, def. mastery 2, hardened skin 3, hp 3
U: pers 3, ghost mastery, exp 4, util mastery 2
If i wasn't, I would still go defensive anyway, since she has to get close, so 0/21/9 may be good. I would get ignite/ghost personally, but it's up to you.
D: armor 3, MR 3, dodge 4, nimbleness, hardened skin 3, hp 4, ardor 2, tenacity
U: pers 3, ghost mastery, exp 4, meditation 1
Or you could go 9/21/0 and go exhaust instead of ghost
O: crit 3, exhaust, sorc 4, archaic
D: same as above
I'm not the best irelia player out there, so take this with a grain of salt. Best of luck scrubbing your enemies.