Skill and nimbleness, literally right-handedness, from Latin dexter, the approved side of the body.
Documented
Dexter and its cousins
Latin dexter (right side) built dexteritas, skill. The family is vast: ambidextrous (both hands right hands, a hidden insult to the left), dexterity, and through PIE *deks- the Sanskrit daksha and Greek dexios, all carrying right plus skill plus favor.
Assessment: Documented: the cognate chain across Indo-European is textbook material.
Stories
The right to rule
The cultural reading: right became right (correct, legal, righteous) because the majority hand wrote the language. Rights, righteousness, and dextrous all ride the same bias, and left gets gauche, from French for left, meaning awkward.
Assessment: Stories: the pattern is real, though right (correct) has a separate Germanic history that happens to rhyme with the bias.
Interesting claims
The body's first politics
The pre-language layer: handedness division may predate speech, primate grooming asymmetries, tool use favoring one hand. Language did not invent the prejudice; it inherited it, fossilized it, and hands it down in every compliment about skill.
Assessment: Interesting: the 90 percent right-handed majority holds across recorded cultures; the vocabulary verdict followed.
Sources and further reading
Lewis & Short, A Latin Dictionary, 'dexter'
Oxford English Dictionary, 'dexterity,' 'ambidextrous'