Change to a nontarget ability that stops attacking the selected target while active. Increase cooldown for pvp to compensate. This would work like Counter, albeit differently as you still take the damage with reflex and it doesn't work against a 1-hit KO. It wouldn't be a direct counter for asal like the actual Counter ability, but would at least provide a useful tool against it while still requiring situational awareness to use effectively in siege.
Blades are still very challenging to siege with. Fun but challenging. Making this change would be a huge situational improvement without making the class OP or having any effect on the other challenges associated with the class. Having sieged several weeks in a row on a geared blade, I express this opinion with confidence.
Seems like an easier fix than the myriad suggestions in the old blade pvp post.