I'm not saying that mastery doesn't give blood shields, I'm saying that versatility negates more damage per point than mastery does because death strike is only a third of our mitigation, at most.
You do not choose between "having a blood shield" and "getting more healing from versatility they're all multiplicative bonuses so versatility increases your death strike heal by 10% which in turn increases the size of the blood shield that scales with the death strike heal.The point is that you negate more damage by increasing all your healing with versatility 4,000 versatility would increase the size of your blood shield by 10%, death strike heal by 10%, consumption heal by 10% and your blood plague leech by 10%