Since the brandish line buff, I feel that they have covered the only real purpose of the SS line (ranged attack of a melee weapon).
For the normal attack, a brandish (combustor, glacius etc.) is faster (the user is less vulnerable) and inflicts a status, compared to DA/GF (I don't count GF status, because 1. it can also be inflicted on the user, and 2. it is useless in PvE). Additionally, the combo does more damage (3 hits taking a similar time to execute as 2 from DA/GF) and and is easier to execute (the player must be standing very close to connect with both hits from a DA/GF, and is vulnerable if the second hit misses).
For the charge attack, a brandish executes immediately, compared to a ~1.5sec delay from DA/GF, inflicts a status (as earlier mentioned), and works regardless of whether or not a player is standing beside a wall. I don't know how damage compares (due to multiple hits) - it looks like DA/GF is stronger, but not by much.
With regards to balance, I have a few suggestions:
Lower damage on the brandish line (an option, but not a very good one).
Make the knockback from the charge attack perpendicular to the direction of the attack (i.e. sideways). This way, the brandish would retain its high DPS, but be less useful for CC.
For the normal attack from DA/FG, lower the knockback on the first strike, and raise it on the second strike, so that both strikes will connect more often, and the weapon is more useful for CC.
Fix the bug with the DA/GF charge attack.
Before I receive a torrent of hate, I don't feel that I am complaining, but expressing my opinion. Please don't reply unless you wish to talk about balance between the two sword families.
Divine avenger and acheron have the same damage numbers, but divine avenger covers more area with its attacks (you could hit 1-2 slags with your combusted, or you could hit 5-7 slags with your divine avenger) and has a larger, more damaging charge. This makes them almost entirely on par with one another, and useful in vastly different ways despite how similar they are to one another.
The reason the brandishes are better in general (and thus so noteworthy) is because of how different their abilities are. Whereas divine avenger deals crowd control, combuster deals crowd control AND single target damage, equally well. The caveat to this is that if you have a capable weapon that deals high damage point blank (like dread venoms striker), then the crowd control from something divine avenger immediately becomes more useful than the overall utility offered by something like combuster. In this way, a better balance idea would be-
Heavy damage swords = slightly higher ramp up in damage+extended range, to encourage their use in the end game
Dread venom striker = higher ramp up in damage, unleash the split damage via shadow/piercing but not elemental damage
Warmaster rocket hammer = first strike now same as combuster's
This way, the brandishes are capable of carrying players through most content, but drop off at some point and become less worthy in the face of other options- especially for pure swordsmen. Nerfing brandishes like you say kind of removes them from the picture, primarily because of the decisions made for the gunner update- why would I use a crummy nerfed brandish when I can use iron slug, winter grave, or callahan?
. . .
Faust and gran faust on the other hand are just poor weapons that truthfully need buffing. The curse status on them is an interesting choice, and could be quite potent if allowed to be... and I think that it should be, in exchange for the massive spreading bullets found on divine avenger.