I cant do lockdown ( my mac crashes) so I can't give you any advice about that. I primarily solo and have found that the deeper you go the more you need to master different styles ( gunner,bomber,swordsman). In danger rooms and at deeper levels you cant just hack you way through. check youtube and ask other players you run with who specialize to give you a few hints.

after a few weeks of solo, it is very crucial that you have to know the main fact is to survive, not to kill as many enemies as you can. Therefore, you should look at all-around weapons, which is normal-speed weapon with average damage, average knock-back and average crowd control. Therefore, swords would be Levi, DA if you're REALLY good with controlling the sword; guns would be valiance and bombs could be Shiver, vortex (again, you have to be really good at bombs) or Nitronome

The most cited solo weapons are bad in team, in general :
- calibur line charge attack is godly in solo, but the knockback will annoy the hell out of your team. Don't use it and it's an okay normal sword.
- pulsar line expanded shot do huge damage, shock and keep enemies out of reach, but the random knockback and disruptive visual effect will get you hated if you use expanded shots on anything save turrets. Be ultra careful at where you shoot and it should be ok.
- nitronome is the worst. It's a solo bomb, period. Its nickname is "the blue screen of death". And the death it refers to is not the mobs death.

I use my nitronome when I'm not playing solo, but I go with a competent partner who knows how to use the fuse line as a cue to time certain actions. More than once it has saved both our butts in an arena. When overwhelmed, just run to the bomb and shield until the boom creates some space for you.

When I solo with only two weapons, I like an elemental status-inflicting gun (for turrets, retrodes, and pretty much anything you can shoot) and a stratum-appropriate sword (shadow, piercing, or normal - never carry only two weapons of the same non-normal type). In a beast stratum, for instance, I'll have a snarble barb line sword and a cryotech alchemer. In a jelly stratum it'll be kilowatt pulsar line and nightblade. In a freeze stratum, firotech alchemer and vile striker.

I usually have 3-4 weapons, though, and take 1-2 bombs then. Nitronome is my favorite bomb, followed closely by the fiery vaporizer line.

Blast Bombs are meant for their Potential knock back along with its damage while the spine cone deals piercing damage and I think 3 star Twisted spine cone and higher, It can knock down soft bodied enemies such as Gremlins and Wolvers. As for Blaster/Alchemer combo, each shot of the Blaster and its upgrades give a knock back against enemies, and when you have nothing you fall back on,; the Blaster is an all-around gun since its does Normal damage. No one can resist Normal damage. As for Alchemer. there are elemental alchemers you can choose from Voltech, Cyrotech, and Firotech. Prismatech lines doesn't have any status effects,but it trades in for slightly more elemental damage while the Shadowtech lines are pure shadow damage (no status effect). All in all, i hope this helps.