I think Cerberus' use of medieval-style armament was a nice touch.
It wasn't JUST a sword or a buckler though; with the Cerberus Guardian, it's explained the the shield is a "polycrystalline composite" and "the weight of the shield requires an armored suit equipped with hydraulic assists and a dedicated power supply."
The usage of such "antiquated" equipment also lends a bit of classy to Cerberus, fitting their self-image as human supremacists.
And with several of their units, it's stated that much of their power on the battlefield comes not just from their superior weapons, but from the psychological tactics they employ.
Assault Troopers are fearless and coordinated, and if you're not careful, they will have you right in range of an Atlas or a Phantom.
Guardians advance relentlessly, and unless you know where to aim or have piercing capabilities, they never stop.
Engineers can remain unnoticed until you find yourself under fire from multiple auto-turrets.
Nemesis are practically invisible, but then your shields are gone from out of nowhere.
Atlases are great... to blow to pieces. But try to get out of range of it's gun and you find the guillotine.
Phantoms use a "monomolecular blade". Yes, I hear what others mean when they say "But Omnitools are better!" But look at it this way.
Phantoms don't need an omnitool to craft their blade for them. They can use a more traditional model because they're THAT GOOD at what they do.
Even their palm blaster is basically a high-tech shuriken, and it's just as effective.
One hit, shields down.
Two hits, health critical.
And now it reappears behind you and you get a close-up look at their blade...
Dead.
I found the Cerberus fights to be among the hardest; Reapers are large and scary, and they hit hard, so the response is to just hit harder until everything is dead.
Geth are like a Jenga tower, you have to dismantle it one piece at a time. If you can prevent them from winning in attrition, then it's manageable.
Common to both groups is that their tactics are singular, with reliance on either superior numbers (Reapers) or a network (Geth).
With Cerberus, however, it's a mixed bag. You take out the Assault Troopers because they have no protection... well now a Guardian is using his shield for batting practice and you're the ball.
Okay, so instead you focus on the Guardian, finally taking him down or at least removing the shield. Now you have grenades at your feet, and the only way out is to go directly in the line of fire of a Nemesis.
Point being, Reapers are like a giant hammer. Find a safe spot from the hammer, and if you can manage to not be pinned, then it's a simple matter of FORCE vs FORCE.
Geth are like a web, if you get caught in it, you're stuck; so stay at a distance, find a thread, and pull.
Cerberus...
There is no safe ground, you find cover and they flush you out, you take out the Atlas, there's a Phantom behind you. Nemesis draws a bead on you so you take it out, and now you're flanked by Assault Troopers.
Needless to say, I like fighting Cerberus because it's always exciting, almost a battle of wits as much as a battle of arms.