Lightning
That's it just use lightning. Ship hulls are usually metal which distribute electrons (as present day planes do), but even a small current across the body can cause defibrillation of the heart. You could explain that to allow people to move quickly they use kevlar / ceramic / non-conductive armor.
Regarding your particle ask. It turns out different wavelengths of light are absorbed or reflected differently. Light is transparent through glass, but it absorbs infrared wavelengths. You could establish a new wavelength which is reflected by the metal on your ship, but is far too heavy to wear (think wearing uranium / lead blocking X-Rays works, but is not practical). You could have some "tank" troopers which do wear such metal, but they are easily killed by lightning grenades which is why armies no longer use them.