Power Fist: The cestus, yes; the spiked gauntlet, yes; the electro-zappy-glove, yes. The true power fist, however, as seen in Fallout, et. al., generally comes attached to a set of Powered Armor, or at least a power torso – in the interest of not ripping your arm off when you try to be Ms. Punchy – sorry, Veronica – or at least straining something quite badly.
(This rule is, of course, void for appropriately built cybershells.)
Loud of War: What the war pipes were originally invented for, and never mind their usage to rally and direct the troops. Also, if you recall the lampshading of the lack of battlefield stealth under Bling of War, what the speakers on the Powered Armor and Awesome Personnel Carrier are often abused to do.
(It is actually not military policy to advance to a rousing chorus of “Behold, The Gods of Thunder Advance”… merely military practice.)
Collapsible Helmet: It may – indeed, it does – qualify as Awesome But Impractical, but in situations in which you are, say, being shot at and as such may lose vehicular atmosphere Real Soon Now, it can also save your life.
You do have to mind your hair, though. Or instruct your nano-enhanced hair to mind itself. Either works.
Bottomless Magazines: Not literally true, but due to the architecture of modern Imperial firearms, it often seems that way. A typical example has three types of “ammunition”, in a consumables-you-need-to-fire sense: a metal-containing “magazine cartridge” that the flechettes the weapon actually fires are produced from; an energy cell to power the mass driver that makes it work; and a heat sink (containing the same high specific heat capacity thermal goo we’ll be talking about later in Deflector Shields) to give you somewhere to dump the waste heat produced by said mass driver so your gun doesn’t melt.
The flechettes are small enough and light enough (grain-of-sand size, made up for by extremely high velocity) that by and large you should never need to change the magazine, even in a whole sequence of firefights of unlikely length, although you may want to swap in a new one at maintenance time, just to be sure. The heat sink usually only needs to be swapped out at maintenance time (the goo may eventually crystallize), because in normal operation the radiative striping on the gun should be able to get the heat dumped in between uses, but if you routinely keep up sustained volumes of fire, you can carry some spare heat sinks with you and field-swap them to let you keep it up beyond what would otherwise be the weapon’s thermal limit. The energy cell is actually the thing you’re likely to need to swap most often, and it usually holds enough energy for a good couple of hours of firing, so while you may need to change it, you still probably won’t need to change it that often.
And of course, those magnificent legionaries in their combat exoskeletons have their guns plugged into the much larger energy and cooling reserves of their armor, so those guys really do have de facto bottomless magazines.
Powered Armor: In multiple kinds. Regular legionary armor (also used by the Watch Constabulary, and indeed similar suits without the militarization are used in the civilian construction and other hazardous-environment industries) provides only moderate power-assist, but does come with kinetic barriers, self-contained environmental support/NNBC protection, medical and tactical computer support, and limited vector-control flight ability. (Although those limited assists do still let you wuxia it up with the best of them… only with overpowered guns.)
The full combat exoskeleton of a heavy legionary is a walking tank with interchangeable heavy weapon packs that turns it Up To Eleven, letting its wearer punch out small buildings, throw respectably-sized vehicles, dance a merry jig amid venting fusion plasma, and toss around nuclear grenades at close range. (And yes, they have civilian versions, too. They’re used for things like cleaning up melted-down reactor cores from the inside, while they’re still hot.)
Both of them include substantial mesh-networked combat drone control capability.