Alrighty, as you do not know how PvP works on MCSG, let me break this whole thing down...
You want Sword PvP alone to be nerfed with a quick little SethBling plugin that will alter MCSG PvP severely.
With my MCSG knowledge, I can safely say that 9/10 fights use a secondary PvP weapon (Bow, FnS, Fishing Rod, etc.) This means adding a plugin that changes only Sword PvP does not and will not make sense.
Your argument of saying Sword PvP is boring, but if you were on a rare occasion to have an only Sword PvP battle, I would vouch for MCSG saying those fights are intense, using Strafing/Block Hitting strategies.
Even if this or something similar were to be added, people would leave MCSG, as you can see on April 1st, people weren't too keen on the swordfish update...
To wrap this up, this I can guarantee will not be added to MCSG based on my knowledge of MCSG
Said by a Bacca...