A Domi with a sensor booster locks more slowly than Ishtar with T2 cloak. Hmm. They could use a very little bit more scanres.
The other thing, besides “just add more EHP” is to put a role bonus on all the battleship to double the effects of plates on it, or to make bigger buffer modules which battlecruisers will have trouble fitting (maybe XL shield extenders/3200mm plates).
The ability to take damage for a teammate is pretty much a carbon copy of the “guard target” mechanism on tank classes in other MMOs, and… might be interesting. That would be especially useful for spider-tanking. It would also enable dirty tricks: if you can’t guard a guarded target (common mechanic and probably important because of what would happen with spider tanking if this didn’t exist), the enemy fleet could guard something it wanted to kill before opening fire, then pull guard right as it started shooting.