to keep it simple: combine the buckler and longsword into an offhand parry dagger for rogue to use.
its skill would raise the dagger in a defensive stance like the longsword for a short time, and being hit during this would then automatically parry the attack if it is 4 or under impact—the attacker would then be dazed for 2 seconds. It would not damage the opponent as you never actually strike back.
rogue has far too few defensive options to be a super squishy class that needs to get in close to have an effect.