Generically, I've always read that if you can't upgrade both at the same time, get the weapon first. However, there might be an exception in your case. Are you moving up to Tallum Heavy? If so, you might want to do some research. I can't say what moving from BW to Tallum Heavy is like. But I went from Doom Heavy on my Destro to a set of Tallum Heavy that a clannie let me borrow. That was like getting a weapon upgrade in itself.
As was stated, if you are going Majestic and Kesh duals, get the duals first.
Strongly suggest you craft them. Cost 115KK in Gustin right now +4. Craft them and successfully enchant them would cost a fraction of that.
I went dual damas and Tallum heavy. Pretty happy with it, but... I got the dual kesh's for my subclass quest and the friggin things do as much damage as dual damas, just hit faster.
Dual Swords that have the Haste SA are inferior to the Dual Swords that give the Focus SA. There are no Focus Duals in A-Grade. The Focus duals with the most P. Atk is a Tsurugi*Samurai Longsword, which is B-grade. B-grade soul shots cost less than A-grade soulshots and, due to the boost in critical, you'll crit more often and therefore use less soul shots per mob.
tsu*sls is the best PvE duals in game, me thinks. but for a glad, and if you PvP anything, I would go either with kesh*kesh for the atkspeed, or kesh*dama for more health.
(or in interlude get the new top Agrade, also atkspeed)
A gladi I know went tallum and kesh*kesh (+4). I think he got his armor first, but definitely enjoyed it more when he got his Dual +4 Kesh.
Like others have said though for PvE and for some PvP crit duals are much better. Recently my friend got a hold of some +10 Samarai*Tsu swords. Obviously these are better than the Kesh because they have more p.attk and have awesome crits. My friend is deciding if they may actually be better than the kesh because TSS can crit, and when it does it is devastating.
The jump from BW heavy to either Tallum or Majestic will feel like a weapon upgrade though. My advice, upgrade to whichever will be easier. If you get a hold of some stuff to craft a tallum helm, get ur armor first, if you get a hold of some kesh stuff and some A weapon enchants get those. Keep in mind, in order to notice a large difference with your weapon upgrade, you will have to be willing to get them to +4. If you don't, the upgrade wasn't worth it, and if you break them, you must make sure you aren't stranded. 60% crafts with roughly 60% OE success rate, and you are looking at a gambling game.
Also another thing to notice is Kesh swing faster and A grade shots are more expensive. So if you are already struggling to get both, using the A grade weapons are going to eat into your expenses a bit more; this may create a adena problem to get your armor.
I would highly suggest against getting a maj set to start w/, if your in a cata w/ stun mobs then ur most likely gunna have a healer to help u out. I would go w/ tallum because u can survive in mass pvp just fine w/out having the stun resistance, u can carry more shot which means u can grind longer, u can swing crazy fast w/ haste lvl 2(or gsap), dualist spirit, tallum heavy, and kesh*kesh +4. I've tested it and it falls short by a few points of a tyrant w/ the same buffs (when the tyrant isnt using fist fury).
As for duals, im waiting until interlude and then im going to craft DLE*dama and then oe them to +4. If you can manage to get ur hands on tsu*sls +10 or so use that for A grade because crit SA owns a haste SA. But those are expensive and extremly hard to oe urself. So i would suggest getting tallum heavy and kesh*kesh (or wait it out till interlude like i am). DO NOT get dama*dama, yes they have the most p.atk. but u dont need the SA at all. gladi's have great accuracy w/out them and u can make up for the damage w/ ur atk.spd. or u can make up the damage u take w/ the health SA. Either way u look at it u dont need dama*dama, even if it looks kool.
I've played along side a gladiator for almost 2 years and watch em go through many set-ups and the one that worked out the best was OE'd Keshes and Tallum Heavy. Granted the keshes were +8 though. It was a pvp set up...the atk speed from the duals and armor allowed for faster charges/skill execution and recharges. Face it, you only swing as a gladiator in a pvp if your out of mp :P
And yes, regardless of how they look or considered "top" A, dual damascus are useless to a gladiator. Haven't seen a gladiator skill miss yet :P
As far as I'm aware, some tests have shown that the actual physical crit rate had nothing to do with skill crits as of C4, I'm not sure after that. :) But it might be worthwhile checking again.
The Keshes are nice for gladiators in PvP since they help skills reset faster, but Dama*Kesh is also nice for the health boost there. ^^
I've read and I think Dama*kesh +4 and Tallum is the best. Tallum gives me 8% Atk. speed (like Kesh*Kesh +4) and Kesh*Dama +4 gives me 25% HP (perfect to compensate the -2 CON of Tallum).
<------ got +4str +4dex -8 con and thinking of keeping my +6 Tsu*Sls and go Tallum heavy for my glad, PvE strictly, whats your take on that guys? ^^
i just dumped my +dex -con tats (+3 and +2 dex, both -con). Still swing about the same rate thanks to duelist spirit, and get stunned in pve a LOT less. -con was ok for pve for a while, but... once you hit duelist spirit... i'd dump it. In PvP it the extra hp/cp gives you enough time to actually do something about it too.