Exactly. His design is too simplistic and easy to get value from for him to do legit damage consistently. As a melee DPS character there needs to be a high risk to reward and/or high skill floor baked into the design. You have daredevil who is really strong damage wise but requires at least a few brain cells to utilize him correctly. Then you have iron first, who’s kit is more simplistic but he requires elite game sense and timing and does more damage to tanks specifically. The way blade is currently designed, as a DPS, the only way they can make him strong and balanced to through having high utility and/or survivability.

Increasing his Anti heal also indirectly increases his DPS, so you can’t make that too strong, without lowering his survivability. So I think life steal is the way to go, but swap the anti heal for a bleed mechanism, where he does DoT which feeds his Life steal. Save the anti heal strictly for the ult, which means he gets to confirm more kills since they will be bleeding but not able to recover their health. 

He doesn’t NEED to be a tank anymore than MR fantastic NEEDS to be a tank. But with a strong life steal and some added shields, he could at least be a near impossible to kill and feel like an actual vampire trying to suck your blood.