The vibromatic blade uses a high frequency vibration to lend superior cutting power to an edge. Essentially a high tech electric turkey carver, a vibromatic blade typically has a single edge mounted on thin, rubber-coated dowel. Any decent vibromatic has strong shock absorbers installed in the hilt, minimizing the numbing effects of clutching something thrumming.
Some have argued that such weapons have diminishing returns the stronger the wielder, as the strength and size of the swing would effect cutting power more than a high frequency vibration. But there is no denying that they are better at sawing through sub-dermal plating than a non vibromatic weapon.
Double edged vibromatic weapons certainly exist, though slicing all the way through an object presents it’s own challenges when both edges are whirring at high frequency.
Seeing as the blades are typically small and lightweight, vibromatic weapons are almost always sword like: katanas, glaives. A vibromatic axe is certainly possible but less effective, seeing as the thicker the blade, the more erratic the vibrations. Impaling weapons benefit not at all from a high frequency vibration so no one produces vibromatic shivs, spears or darts.