blade has 5 distinct synonyms spread across 3 of its 9 senses. Each sense below keeps its own list, because a synonym belongs to a meaning and not to a word: swapping one sense's substitute into another sense's sentence is how a thesaurus makes writing worse. WordNet records no antonym for it — antonymy is a relation between word forms rather than concepts, so it is deliberately sparse.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
especially a leaf of grass or the broad portion of a leaf as distinct from the petiole
a dashing young man
“gay young blades bragged of their amorous adventures”
Synonyms, antonyms and the broader and narrower relations for blade come from Princeton University’s WordNet. Full sources and licences.
something long and thin resembling a blade of grass
“a blade of lint on his suit”
a cutting or thrusting weapon that has a long metal blade and a hilt with a hand guard
a cut of beef from the shoulder blade
the part of the skate that slides on the ice
flat surface that rotates and pushes against air or water
the flat part of a tool or weapon that (usually) has a cutting edge