How about:
motif
Definition: central theme
Synonyms: concept, design, idea, logo, notion, pattern, structure, subject
element
Definition: essential feature
Synonyms: aspect, basic, basis, bit, component, constituent, detail, drop, facet, factor, fundamental, hint, ingredient, item, material, matter, member, part, particle, particular, piece, portion, principle, root, section, stem, subdivision, trace, unit, view
quality
Definition: characteristic, feature
Synonyms: affection, affirmation, aspect, attribute, character, condition, constitution, description, element, endowment, essence, factor, genius, individuality, kind, make, mark, name of tune, nature, nature of beast, parameter, peculiarity, predication, property, savor, sort, trait, virtue, way of it
Or from the world of Object Oriented programming: property (and skills are methods ).