But there's also the fact that to "cancel out" a properly build plasma blade, you'd need a shitton of water, simply because of the incredibly high temperature of the blade; raindrops would vaporise well before coming into contact with the plasma itself. "Dispelling" energy isn't as simple as it seems. For example, the only way to completely negate a laser weapon would be to 1) use a perfectly reflective material (which doesn't exist) or 2) somehow refract the laser without it burning through whatever medium is used to refract it (maybe an energy field?). Physical weapons can also easily be deflected, mind you. If I had to choose between using armor to stop a metal sword and using armor to stop a plasma blade, I'd go for the metal sword any day.
True, but again remember what reality we are in. The game starts off on Em-8er but the idea is to also go to other worlds. And there many things that exist on other worlds that don't exist on Earth. For example, within our own solar system, there are lakes of liquid natural gas on some moons (Lol, I would love to see people try and use energy weapons on worlds like that just to see if they set the whole planet/moon on fire), cryovolcanos (there are places so cold that the hottest things the volcanos can shoot it is ice and frozen stuff), worlds with super-sized rain drops that fall down in slow motion (a combo of gravity and atmospheric pressure). Water is not the only thing that can take away heat from objects, is just one of the most common things that people run into on Earth-like worlds.
Plus to make a plasma blade keep its shape you need to also be able to control the magnetic field that is keeping the plasma in place. So anything I do to effect the magnetic field would also affect your blade. What if I know the frequency and polarity of your plasma weapon uses? One of the things I can do to protect myself is to basically make a magnetic field to shield me that matches the one your weapon has but more powerful. Now your plasma bullets and plasma blades can't even get close to me because alike magnetic fields repel each other. And because my magnetic field is more powerful you and your attacks will be the ones who is pushed backwards, not me.
As for laser weapons, there are types of energy fields that do block light. But why just block the laser when I can use the power of the laser to give me more energy to use against you? I can absorb the energy of your laser and use it to help power somethings else on my mecha, like say giving extra power to my railgun/coilgun/mass driver so I can blast an even larger hole into something.
There is a reason why some of my friends say they hate me sometimes. I'm a sci-fi fan who knows about real science and the art of war, so I can end many fights before they even start by out thinking enemies based on the data I have on them. This why I also like to make characters who are proficient in things like data gathering, infiltration, espionage, and tends to use hybrid weapons that also act as multi-tools based on how they are used.
edit: grammar