Cuz when I think about it, sam/war doesn't really have any strat other than trying to kill the opponent as fast as you can with no additional buffs.
I haven't done PvP in ages, never really enjoyed it. BUT, if the debuffing still works, SAM/WAR has the tools to bring down a MNK.
If the SAM was spamming Gekko versus a MNK, he may be doing it wrong. Yuki and Kasha for blind and paralyze are going to be much more helpful than a little more damage and silence. If the SAM can med up to 200% TP, then a Sekkanoki allows for the SAM to stick both debuffs, as well as do a nice little Compression Skillchain on the Monk. True, it's not the damage of a Fragmentation from Yuki > Gekko. But I'd think sticking the two debuffs on the MNK, as well as taking off a large chunk of health would be worth it.
Of course, if debuffs in PvP wear too fast nowadays, then disregard my advice.
RNG:75 MNK:75 WHM:75 BRD:75 BST:75 SAM:75 WAR:75 THF:75 BLM:75
DRG:72 SMN:63 DRK:55 NIN:49 PLD:42 RDM:41 DNC:37 SCH:37 BLU:37 COR:20 PUP:22
Woodworking:88 Cooking:60 Alchemy:60 Bone:60 Leather:60 Cloth:60 Smithing:60 Gold:54 Fishing:33