Braces are similar to lifting straps.
If you deadlift with straps, your grip wont hold you back from deadlifting more, but it sure as hell wont improve your grip.
Lifting with braces will strengthen the joint for heavy movements, but wont strengthen the tendons.
IMO you should use the brace for heavier movements, but for lighter higher reps dont use it, this way the tendons will be able to be strengthened.
Have you done any rehab work for your tendons?
PS... this is just my idea, I'm far from being a doctor, though.