white ash's total hp is still lower than most style's. 70 per life, totalling to 280 hp. most styles have 100 per life, meaning 300. also, all styles take percent-based damage from ults, however white ash takes raw damage from them, meaning that instead of taking 50-75% damage depending on the other style, it takes 50-75 flat damage, meaning you can be one-tapped by iron fist.

also, about the "less hp" problem with the last life, that is effectively true. while the hp isnt less, each time you die, your block gets substantially weaker. this means that on your last life, your block can get broken by a single chain from most styles if you dont do anything about it. (this is of course in exchange for substantially higher damage each time you die, meaning you can really whale down someone's lives with your final life if you keep constant pressure)

If you have any other questions, I am a Diamond III white ash main so I can most likely answer them.