Diesel tech is equal to real world technology in many regards and behind it in several (user interfaces, programming, electronics and information storage). The area it really shines in is its generation, insulation and direction of gravity (or at least a force like gravity but let us not quibble).
As Winchell Chung has said one of his peeves is gravity manipulation that is merely used to keep everyone on a spaceship agreeing on which way is up. In the dieselpunk setting gravity generators attract or repel the good old sun to travel great distances at appreciable acceleration (usually several meters.)
In orbit around a planet the engines are capable of several gees of acceleration. On a moon or small body generators are purposely built to raise gravity to Mars levels at least two prevent muscle and bone degeneration. Some have touted gravity control as being able to create pressure curtains of air to replace airlocks but sadly these have a knack for pulverizing organic tissue (and soft metals) passing through. They also present safety issues in combat or when a ship takes damage and most of the ways around this involve using a regular mechanical airlock. the irony is not lost on the engineers.
In the case of spacecraft gravity control could be used for docking in a pinch (the control was there but the gravity effects persisted a bit after being shut down) though thrusters worked better. It could create a gravity field on the hull of a ship making space walks safer and repairs a little easier. It could also be used to tractor in personnel and other small objects adrift in space.
The Mercurians were the first to use gravity control for communications. Holding a gravity beam focused across astronomical units was already done for ship drives. Modifying a weak beam to register on a mass detector was a simple modification. True beams could only be modulated fast enough for morse or crude audio, but nothing could stop them. Radio transmitters on Mercury were frequently blacked out by solar activity. The Mercurians implemented a massive upgrade to a gravity wave system.
It was the Earth that used gravity control to invent the blaster.
Blasters were the mythical big wallop pistols so beloved of media. Any physicist will tell you a man firing a pistol at another and knocking them flying is ridiculous. Bullets didn't have that much impact and the laws of momentum would say that the pistol applying such force to a projectile would be thrown violently back. Then someone decided a gun firing a repulser beam was doable and controllable.
A two handed grip was recommended. If you were much below average size you just didn't fire one of the things. This reduced the blaster's appeal. Other problems were the waste heat and radiation that resembled small thunderclaps in an atmosphere. But most embarrassing was the darned thing's tendency to melt and take a few fingers with it. Energy technology just didn't scale down that small.
The problem was partly solved by using resistors in a cylinder. If the energy dump didn't proceed properly, a resistor would blow before it got too bad. It was an improvement as it usually only took one finger (and sometimes only the first joint). Nevertheless some officer somewhere wanted it to work so development continued.
Special Forces issued blasters made an extraordinary effort to lose or break them.They did admit in the hands of a (large) skilled user they were spectacular for sparking confusion. If it fired. It it didn't cremate the user's hands. If it did the confusion was on the wrong side.
Then a bright boy decided the exploding resistors worked better as a design feature than a flaw. Power was dumped into a repulser generator. Some of it went into a resistor (usually a tungsten composite) that vaporized. The small stream of melted metal was 'blasted' away from the weapon and down a column of vacuum created by the repulsion beam a micro second before. The blast had the advantage of carrying waste heat away from the weapon and putting it to some good use. It was hoped the forces of entropy wouldn't notice.
The repulsion beam would hit the target with the force of a sledgehammer, knocking most people flat. The stream of molten metal (somewhat solid after a few meters would add injury to injury actually inflicting a burn and a possible electrical shock from plasma carried along with it.
Blaster pistols held six shots. That was the number of shots judged to be safe for a firer's wrists. In practice users learned to reload the things quickly in a firefight. Rifle versions were soon produced. They didn't have anymore fire power but the recoil was easier to control. Some users added a hook under the barrel to brace the weapon on a wall oral and spare their shoulders somewhat.
The Martian foe is more advanced in energy weaponry than Earth people and has a number of smaller and more powerful weapons including a 'disintegrator'. A disintegrator was capable of turning a human being into a problem for forensic specialists (with microscopes). The exact way waste heat was eliminated is still unknown.
Disintegrators in media are portrayed as scrupulously neat weapons. They hit you, you glow and are gone. In the real world disintegration means breaking a target down into smidgens. Matter is not destroyed but strewn all over the place. Disintegrators would be far more potent if their range was not so limited. They remain the modern equivalent of the Old Earth flamethrower: extremely potent within their range and scary as hell.
Some manufacturers tweaked the plasma created when the resistor blew to create pulses or beams of 'light', actually relatively slow moving pulses of plasma. SpecFor never went in for these features. True you could follow them to see where your beam impacted, but the salient point was your opponents could follow them back to your position which led not end well for you. Some action hero types were portrayed in media as being quick enough to dodge blaster bolts or even deflate them with various contrivances.
In reality the repulsive bolt traveled at light speed hitting targets long before a 'pulse' would reach it and the spray of tungsten was even twice the speed of the 'light'. Attempts by wags to block blasters in the field did not end well. SpecFor denied that it had gotten the entertainment industry to purposely stage such deflection events in their action movies to goad their enemies into suicidal heroics.