How do I use this Saber?

Turians, especially the infiltrator if you want to experience the Saber at its full potential. I don't remember at low levels but at 10 you can kill in one Saber shot gold little shielded units after an Overload. Go ideally with the extended magazine and the damage barrel, with armor piercing rounds.

Umm this would be a really long post if it wasn't a mobile post. Any class or ability that improves accuracy will make the saber better, Geth, marksmen kits, etc. Turian stability also helps it, so all turian kits. Mods are going to be damage barrel and stability mod unless on a turian then you would take something like extended clip especially on turian soldier. Saber is also going to benefit those who hit a high percentage of head shots. It has a very high hit reaction and very good proccing of ammo powers.

It was my first X level UR, so naturally I used the hell out of it.

On a no-pull Justicar, specced for survival and Headshot passive 5b. It was a scrub build, but I stayed alive and learned to hit the head. Reave is a great stagger power, and the Saber is a great headshot weapon. Very good kit for learning the gun, and with the AR weight reduction passive that I now ignore, it allows you to cast as much as you want while carrying the Saber which is a little heavy.

This might be the winner.  I currently use the Lancer I on this kit, but I haven't been all that satisfied with it.

And thanks everyone for all the great suggestions!  You guys are the best!

I only sort of recently stumbled on to the heart of my biggest problem with the Sabre's accuracy.

Its accuracy mechanic is either different from other weapons, or it is significantly more pronounced, but I'll outline what the practical difference is for me.

Before, I would treat it like I would a bolt-action or slow-firing semi-automatic rifle. In most games (and this even includes ME 3 for most weapons) the rather stark recoil and refire time are the two biggest obstacles to firing accurately, and I tend to get a rhythm down that is based heavily on when the reticle returns to its accurate firing position. That works (it works even better if you can shoot with more consistent accuracy than I can) but it has a timing problem with the Sabre that took me until recently to get used to. The Saber (Sabre? Saber? I could Google it but I'm lazy) takes about a half second to a second more to regain its accuracy than the recoil and refire delay. There are probably other weapons that work similarly, but it's less noticeable than with the Sabre.

So my accuracy improved a lot when I deliberately forced myself to slow down when firing. The reticle actually does change to reflect the changing accuracy value, and it's important to pay more attention to that mechanic than to the recoil/refire. The Black Widow's accuracy doesn't seem to suffer from the same timing problem.

As other people have mentioned, accuracy bonuses are very helpful. But if you're not using a kit with much accuracy, try and remember to deliberately slow down a little bit and make each shot count more (while paying a bit more attention to how the reticle behaves, and the impact it has on the weapon's accuracy.)

Off topic:
So this thread made me remember I had a Quarian Marksman video on my youtube. I went to check it and then I realized that my aim on that vid is pretty much terrible and it made me start the game again after maybe one year or something. I took my saber quarksman for a ride and managed to reach wave 6 on that gold solo. And I think I actually played better than in my youtube vid, back when I was at the peak of my ME3MP skill. I fumbled a lot with the controls, pressed shift a few times instead of space to run, got stuck on cover a lot and stuff like that. But my aim is better today than it was then.

Conclusion on topic: Saber Quarskman with drill rounds and a geth scanner is pretty legit if you really focus on your aim. Just abuse the wallhack to stay safe and aim for the heads.

It's probably been mentionned already but since I'm too lazy to read all the comments I'll say it anyway.

Saber is a powerful weapon with good range, damage and stability. I don't feel like you'd really need to enhance precision or stability tbh,
it's good enough as it is. The only too areas that truly benefits from buffs are damage and firerate which is incredibly low for an assault rifle.

So obviously the Saber in GI's hands would be quite deadly (as most weapons are if not all). Turian Soldier with Assault Rifle Amp III and Marksman for fire rate. GE with Hunter Mod for damage and fire rate + Overload (overload helps aiming for those deadly headshots). I did a plat solo with the Saber as a TGI a couple of days ago and it really works well too as you get significant damage boost from 1. Simply being a Turian (Because Turian are awesome) and 2. Tactical cloak. Honestly with the TGI, if you get a AR Amp III you deal a great amount of damage even if you ignore headshots and then again Overload will help you get themp if/when you want to.

For ammo, Incendiary rounds always work well with Overload but if you're not soloing you might as well detonate your teammates power/ammo if they have them and go for Armor Piercing for max damage or Drill Rounds depending on how you mod your weapon and if you have Geth Scan. I personally go with Magazine Upgrade and High Velocity Barrel if I have incendiary or Magazine Upgrade and Extended Barrel if I have Armor Piercing or Drill.

I feel like the GI and TGI are the 2 infiltrators that can potentially make the most out of the weapons. Outside of the infiltrator class, I personnally love the GE because of Hunter Mod and because I love Overload as it can detonate powers/ammo and really helps with the headshot.

That being said you should probably  try different things out yourself and come up with your own appreciation of the weapon.

Another tip that no one has mentioned....

Despite disagreeing with him about​, well, almost everything, Lord Sirian made a good point about the Saber to me once.

Don't ADS with it. No ADS, far less bloom and less noticeable. The innate accuracy of the weapon is such that if you can hipfire well, you will destroy with it.

In particular, this is very valuable against big armor.

Aim down scope.

Pretty much he's right. You can ADS each time in and out if you can tolerate that without seizures. I hipfire a lot and on certain enemies I'll hipfire once then scope fine adjust for a headshot, dragoons in particular.

Ha!

You are aiming, in that you still have a reticule with your weapon at all times on the screen. You are not zooming in, so you have to line up the cross-hairs pretty well to get a hip-fire headshot, but it happens more often than you might expect, and even moreso once you get the hang of it.

I still ADS with the Saber for certain enemies, like a Nemesis/Phantom in cover, a distant mook spawn when I am confident my flank is safe, triple-hit points on distant Ravager/Atlas, etc.

1. Only shoot when the reticle begins to shrink back. Hurry fire is very inaccurate.

2. Aim for head (or weak points).

3. Use Extend Barrel and AP/Drill Rounds.

4. Be used to moving while in zoom.