Always try to approach them from below, not above so you can see their long range attack warning. Dodge their long range attacks by walking perpendicular to the attack. Shielding works too but a hit will take a lot of health off your shield making you vulnerable to repeated attacks.

If you are near one then expect it to swipe at you, so either don't stand close enough to get hit or use a sword with lots of knockback so that they are out of range after you swing. Polaris makes quick work of Retrodes too.

I find it useful to draw them to a corner where they just stand there and shoot their laser beams into the corner and I just pick them off during the recovery. Best to use a gun for that, but a sword or bomb is fine too.

Shivermist will lock them in place, allowing some easy flanking. Watch out though, a laser beam will thaw a fellow Retrode.

The easiest way is to keep your distance and use an elemental alchemer, especially cryotech which can stop them from aiming. Retrode beams can't cross gaps in the floor or low walls, but you can shoot over those, so you can often stand in a safe place and kill them all. The elemental pulsars are also great, but the knockback from those can cause problems if you're in a group, so use them carefully. The cryotech alchemer line is pretty fool-proof.

As other have already said, the other easy strategy is freezing bombs. I usually prefer the gun, but I never go into the IMF without my shivermist so I can freeze the retrodes and mechaknights in the room with the respawns.

Of the swords you listed, the divine avenger is the obvious choice because of its knockback and elemental damage. It will certainly clear room for an escape when you're already swarmed, but in my opinion, the best strategy is to avoid being swarmed by using a gun or freezing bomb.

The key to retrodes is to manage their attacks. Generally speaking they'll do a ranged attack if you stand still (relative to their point of view) out of range of their swipe attack. This is exactly what you want.

Charge your sword and get them to start firing their ranged attack, then duck around and unleash the fury on them from the side. Then back off and repeat.

Don't try to do a full combo right up against them, you'll just get slapped in the face with their swipe attack. If you see the red ring below them, just run directly away from them.

It's a bit more tricky in a narrow hallway, but generally you should be able to stand on one side of the hallway, get them to attack, and run up the other side to unleash your charge on them. If there's a big pile of them in the middle of an arena, approach them in a spiral pattern with your sword charged, hit them, and then spiral back out.

A DA, Brandish or Levi is the sword of choice here, since the charge will guarantee an interrupt so you won't get swiped. Don't go in with a cutter or a flourish, for obvious reasons. Troika is also a possibility maybe, I've never used one, though the charge attack takes centuries to execute so it might leave you vulnerable too long.

I always found those buggers to be fun to fight. Just a bit of advice when fighting them:
1. Heavy sword: always hit once and back up. If you go for a 2 swing, you'll take damage.
2. Medium sword: 2 hits will push them back enough that the attack should miss. Don't go for a full 3 combo.

Alternatively, bring a gun, trust me, it helps IMMENSELY.

Then again, I'm one of those guys that absolutely MUST have 3 weapon slots. Might want to consider that, they're fairly cheap.

I remember that post...What's going on here?

Personally I'd say use that Levi. It's what I use, with success.
In depth: Prep a charge attack, and move in to attack. Don't rush directly at them, circle around as you get closer. Once you are near, just use the charge and fall back. It works fairly well on large groups too, since the impact stops any attacks from hitting you.

1) Aw damnit he's back.
2) Certainly doesn't look as if he stole your account. If he did steal your account his forum username would be the same one as yours, which it's not, it seems. Additionally, sure took you a long amount of time to get something done about it!
3) Keep the god talk out of this.

Ehsanman has every method to re-acquire his 'stolen account'. The time that has passed since his first claim to its ownership and this day has been extremely length and I'd say it's his own problem if he has not been able to deal with the situation.

...so please stop demanding that this guy your accusing gets hit by a bolt of lightning or dragged down into some fiery crevice, all this holy talk is rather petty and frankly insulting to bring to a game forum and an issue like this, it does nothing to help your case and likely makes people dislike you more then anything so stop it with all this god and religion stuff and just swear or troll like most disgruntled people would on a forum, anymore religious ranting should get you banned if you ask me.

Edit: And what is with that 'woman' comment? What the hell is that about? You say your from Persia, as in Iran or something? It's a freaking game leave your politics and religion out of it.

-Use an elemental weapon!

-Smack them hard!

-Hit them down to the floor!

-Use charged attacks!

Avatar Day! Yip! Yip!