From Late Latin 'bilanx' (two-panned scale), via Old French — the abstract sense of equilibrium grew from the physical weighing device.
An even distribution of weight; a state of equilibrium.
From Old French 'balance,' from Late Latin 'bilanx' meaning 'having two pans,' from 'bi-' (two) + 'lanx' (plate, pan of a scale). Originally referred to the weighing device itself. Key roots: bi- (Latin: "two"), lanx (Latin: "plate, pan of a scale").
The zodiac sign Libra literally means 'scales' — the same instrument that gave us the word 'balance.'