4/25/1 Masteries - ARP-ARP-Armor/L-MR/L Runes
I've been playing Irelia through my Dom career fairly consistently and I've got a pretty good grasp on her, but I'm still trying to figure out between the AD/AS shifts in the store and itemization options how to build her.
My build usually ends up something like Boots - Triforce - Cleaver - FH/Randuin - Sanguine - Maw in absolutely no particular order with Odyn's, Zephyr, Thornmail, Wit's End, Ghostblade, and LW all making guest appearances. Start is always Boots/Pros/Pots, no exceptions, and Phage/Brutalizer are grabbed first equally as often but both are almost always grabbed before other items unless I base/die with enough gold to get a Sheen whole. Triforce is usually finished first because of how much gold I have to sink into it and because the components clog up inventory space otherwise, but unless the game is going way in my team's favour I rarely finish it without all or most of my slots are filled with components. Cleaver usually comes next and from there I gear solely based on what damage intake is a problem: Chain Vest and NMM/Hex are picked up as soon as necessary and finished when either I need the stat on the finished item or I don't have anything else left to buy.
I don't go AS because she has a low cooldown ultimate with a 2.4 AD (I vaguely remember Khazix Q having that ratio on a 2-3s CD. Lul.) ratio and Bladesurge is spammable with some CDR. Armor is less popular now, AS is worse, and her AD options are better than they were previously, so I don't see why I shouldn't shift towards damage especially because short of health stacking (pointless against Torch spam anyway) there isn't much point in defenses past one or two big MR/Armor items to keep from getting cut to zero against BC/LW or Torch/VS.