Passive - Berserker Rage
Olaf's attack damages increases by 1 for every 2.5% of his missing health. (capped at 39 of AD)
His actual kit have much atk spd redundant, personally a bad design, so put more AD when he its nearly to dead make him feel like a true Berseker.
W - Vicious Strikes
PASSIVE: Olaf's attack speed increases by 1% for every 1% of his missing health.
ACTIVE: For 6 seconds, Olaf gains bonus lifesteal and bonus attack speed. During this time, Olaf also gains 1% enhanced healing from all sources for every 2% of his missing health.
ATTACK SPEED: 20 / 30 / 40 / 50 / 60%
I need to Add his actual passive in someway because that make him feel like a Berseker and turn him more "dangerous" when its nearby to die, si this passive can't be lost at all. But keep this passive have a cost and that cost is cut the active part AS. the life steal part keep at the same.
Can't be activated during Ragnarok.
R - Ragnarok
PASSIVE: Olaf gains bonus armor and magic resistance.
ARMOR & MAGIC RESIST: 10 / 20 / 30
ACTIVE: Olaf instantly gains the effects of Vicious Strikes at the 150%, removes all crowd control effects from himself and becomes immune to them for 6 seconds. During this time, he doubles the passive bonus and gains bonus movement speed that decoy over time.
MOVEMENT SPEED: 30 / 40 / 50 %
So with these changes he now can used his Ult to engage and init team fights like a unostoppable truck, also can use to split pushing and run away safe. He loses the flat amount of attack damage but gain a massives tools to engage on team fights rushing into key targets. Instanly start with a pumped Vicious Strikes effects to make him feel like a real Berseker for 6 seconds and a real nightmare when he is close to die.
This Olaf its by far more funny, spamming axes like a crazy, and engage in tf like a truck, split pushing more safe, and make his Berseker thematic much revelant.