It's a DiaCompe aero lever with the old, specialized ferrule.


>> Sometimes the point where the cable housing mates within the aero lever can become a point of compression, where the housing is "drawn inward" through its stop in the lever slightly. This chews up the outer plastic covering, and prevents the cable from relaxing quickly, as the housing eases back out from its stop when you release.

Just check to make certain that the housing tip isn't chewed up. That'd be the sign of a problem there.