Should never punish players for something like that.
For making a ridiculous build which is clearly just exploiting a stupidly OP weapon?? It's not like it was one guy running around. People knew what they were doing, they made their bed. Besides it always seemed to be alts/STF so it's not like it would have cost anybody that greatly if it was nurfed without a respec, especially after you consider the amount of gold they will have generated by playing with almost 0 upkeep.
Though tbh I blame you/other devs for including it at it's current stats for so long, not the players. People will always exploit any game mechanic they can to get an advantage. It should have been nurfed hard and fast after seeing it in action. IMO all updates/patches should be given a week or two then reviewed and adjusted as necessary. Then again maybe it's not the roundel daggers fault, maybe it's shields not requiring strength which allowed them to have such stupid yet successful builds. Either way, you're the item balancer and I'll leave it up to you.
Anyway, thanks for keeping us updated with the current plans