Thing is, these days a WS that is good both inside and outside Abyssea is pretty hard to come by. Most of them involve building a specific ultimate weapon which I'm sure you're not interested in (EX: Ukko's Fury, Victory Smite, Chant du Cygne, Blade: Hi etc), thus you get merit WSs. I think you should decide on which jobs you are more interested in playing outside of Abyssea often and get merit WSs for them, because damage you're doing inside Abyssea isn't as big a deal.
I'm actually not sure what jobs you even have, but I do know that Shoha is actually the best SAM can bet on unless they have a Masamune, in which case they can spam Tachi: Fudo, so maybe you want to keep that one.
The Scythe VS Great Sword problem is probably hard to balance, because both Scythe and Great Sword are slashing, so it isn't even like a case of Staff VS Spears for DRGs, where a DRG might melee in a staff with their B skill when they're fighting a skeleton or something really strong to piercing. Ultimately, if they decided to just make Entropy a top-end damage WS like Resolution, it would mean that DRK has a choice between damage or damage, and math wizes across the internet will eventually find out one trumps the other and the other will fall into disuse for DRKs (which has happened multiple times, from when DRKs favored GSDs thanks to Spinning Slash and /THF, then they went back to Scythes after some adjustments, and now they're back to using great swords again). The director implied at one point he wants to encourage more use of a variety of weapons, though (he mentioned something like trying to give each weapon type its own unique properties), so maybe there's something to look forward to as far as that goes.