I did consider that, 25 vit over 5 accessories, 363~ hp. As an FYI, twintania doesn't do a lot of insane damage other than death sentence with autoattacks/plummet that can land at the exact same time which is why health is such a huge stat against her. Sure the random parries/blocks will help over the duration of a fight but if your healers can't heal through the autoattacks and plummet then you're never going to do the encounter. You're gaining a 2% additional chance to parry for 1 extra percent of mitigation. However this is purely BiS which to be honest is fairly rng based to get in itself.