Life Leech triggers on melee hits, so it works with Armor Ignore. The area effect of Frenzied Whirlwind however isn't considered a typical melee hit though, so Life Leech doesn't trigger on the secondary damage. Your pet queus FWW and lands his melee hit on his main target, and that triggers an area effect which is guaranteed to deal damage based on Ninjitsu skill, requiring no Hit checks vs the secondary victims. It technically functions differently than the usual Whirlwind (which did pair with Life Leech). The actual Whirlwind ability (which is now unique to Bushido Magical) would trigger upon the pet hitting it's main target, and then trigger the usual Hit checks vs the surrounding enemies (WW can miss secondary targets, FWW can't).
One of the great things about the Chiv+AI Ossein Ram, is that they can actually make use of the Taming Mastery "Combat Training: Berserk". Normally, Berserk triggers while the pet is under half Health, and it'll ramp up the pet's damage resistance (against all elements, unlike Empowerment/Consume that only function against Physical) and damage output, but also greatly cripple any healing the pet receives. The pet will remain Berserk while under 50% Health and in combat, or until they die. If they exit combat while under 50% Health, they have to be healed above 50% before Berserk can trigger again. While Berserk, HPR is reduced by 90%, and Veterinary/Greater Heal/Cleansing Winds/Gift of Life/Close Wounds/Heal only heal a sliver of health. For most pets, Berserk just transforms them into a Kamikaze, they're eventually going to die, but they're gonna dish out some serious damage before then.
The only form of healing that seems to bypass this restriction for pets, is Life Leech. I've seen my 120 Chiv+AI Ossein Ram (Zeliek) deliver a 347 damage EoO AI (highest damage i've seen any pet deal in a single hit) to a Paragon Balron before while under Berserk, and simultaneously heal himself for 150+ Health. While under Berserk, a 120 Chiv+AI Ossein Ram becomes both incredibly lethal and tanky at the same time. They have to be able to reliably land hits though to keep themselves alive, so 120 Wrest is practically a must and foes with extremely high Wrest/Parry cause them problems. When combining a berserk 120 Chiv+AI Ossein Ram with a 4x120 Bard's "Inspire" (+22% HCI/+58% DI/+15% Damage Modifier) or an Archer's "Play the Odds" (+45% HCI/+30% SSI), they're incredibly nasty, a damn near "God Tier" pet then.