The Powered Melee Weapon
The improvements in armor and armor suits in the Cosmic Era have made close quarters and hand to hand combat a good deal more difficult. The kinetoresistant material in an encounter suit render punches almost useless while SLAB armor renders most civilian grade weapons as effective as pellet guns. There are guns large and powerful enough to negate these armors, but it isn't always practical to carry a shoulder mounted weapon, and there are often range considerations for these larger systems. This has pushed melee and powered melee weapons into the forefront of combat technology.
There are many that are well known by the public, and the subject of their own mystique. The Hyperedge and progressive blades in the hands of trained specialists has become the katana of the 25th century, able to slice through tank barrels, remove limbs from power armor, and even cause serious damage to mecha. Likewise, the Lightning Claws, a set of much smaller hyperedge blades set into a bracer, have existed in popular culture long before the advent of the actual technology. These weapons are indeed popular and effective, but there are few things that draw hostile enemy fire faster than a soldier with a sword, and using lightning claws is a very up close method of fighting. This leaves the soldier in the way for counter attacks, and unlike the power of the larger blade, the claws are limited in their penetration ability.
None of these are effective weapons for anything other than assault troopers, close combat specialists and melee power armors.
The Progressive Stiletto
The Stiletto is an archaic weapon, little more than a sharp spike with a handle on it. Originally used as an assassins weapon, it made a small puncture wound, and was heavy enough to punch through bone, like the skull. While this is of little use against power armor, the powered version of the weapon has several tricks up its sleeve.
The spike itself is a powered weapon, though it is a one shot usage. The spike is able to penetrate several layers of armor before its power supply is exhausted. This will cause the stiletto to become stuck into whatever it was stabbed into. The handle of the weapon contains more than just a micro-power cell, it also contains a small amount of a formidable explosive. Once the weapon becomes stuck in something, the timer activates and a few seconds later the charge explodes. This stabbin' grenade is an effective way to damage or otherwise hinder a power armor trooper. It is brutally effective against standard light armor and for removing obstacles like light doors, or making new doors in walls.
The blast is seldom strong enough to kill a heavy armor trooper, but it will compromise the function of an arm, destroy a firearm, or effectively cause a critical hit against whatever part of the armor it was stuck in. A fast thinking soldier can remove a stiletto, but while he might prevent damage to whatever it was stabbed into, it will likely cost him his hand.
Usage
The main users of the progressive stiletto are scout and recon power armor troopers and many special forces troopers will carry a few of these weapons. In actual 'trench' scenarios, the stiletto lacks the penetration or stopping power to be a regular use weapon.
Author's Note
I had the idea for the stiletto after thinking about how something like a Starcraft Ghost, or other specialist soldier (Metal Gear Solid, Tekinin cyber-ninja, etc) would go toe to toe with a heavily armored soldier. The stiletto is rammed home, possibly as an off-hand attack and then the attacker would fall back to let the explosive do its work. The exploding stiletto would naturally work well for making holes in things, like walls and doors, just as well as making holes in armor or people.