More precisely, it's similar to a highly vibrating sword. They're extremely sharp and can cut though a lot of things like light sabers but they aren't "lasers". They're also a symbol of nobility hence, for normal people, seeing someone with a sword means "he/she is a noble" (that's why the two guys who were trying to flirt with Serena in a previous chapter, ran away as soon as they saw her sword).

However swords do have a few problems:

One of those problems is pretty obvious: You need to get close to the target in order to cut it. In that world, it's more difficult than expected as most battles take place in space. The ship used by this noble before was created due to the nobles' insistence (or more exactly: fanaticism) and, despite having powerful shields & great speed, it's still called an "expensive coffin" due to its low success rate.

Another problem that swords have is that... Well... While they cut though most things, they can't really cut though shields and hulls. Hiro's power armor offers quite a lot of strengh and powerful defenses (at the expense of speed) so that's why he's saying a "Too bad for you" at the end of this chapter: He's fine.

And there's also a limit in what humans can do. That's why pretty much all nobles use implants to boost their body. Some implants can help them manage their territory and do their work. Some can boost their physical abilities like strengh, agility, reaction speed. Reaction speed in particular is quite useful in order to deflect lasers.

just as dark said.  in WN and LN. its mostly shown in illustrations or explanations. for example. in the WN. this guy its using an exo skeleton that help him boost his phisical abilities. but here in manga he its using a noble outfit. if i remember in WN. that noble its described like Raiden from metal gear. well.  soon MC will know thats the price for defeating a noble XD