Sun in Libra
The Sun in the sign Libra is a debilitation placement: will through partnership, diplomacy, and a sense of measure. Libra is the seventh sign of the zodiac, airy, cardinal, ruled by Venus — an adversary of the Sun in the traditional planetary friendships; this is the Sun's only true sign of debilitation.
The Sun in Libra is constrained here: a will used to asserting itself directly is forced to find support through partnership and measuring its steps against others.
What this placement means
Libra under the rulership of Venus gives two effects. The first is a sense of measure: a person tolerates extremes poorly and seeks balance. The second is a capacity to negotiate: here the will shows up as a knack for bringing two sides to common ground.
The Sun in Libra needs a partner. A setting where every decision is made alone leaves it without the support it's used to asserting itself through.
The Sun crosses a sign in about a month, and this is when the yearly highlight of the same channel of will falls: over that month, what's set by the placement in the chart is lived through. Lasting influences come through the slow planets' transits over this sign — Saturn crosses a sign in about 2.5 years, Jupiter in about a year — and through the mahadasha of Venus as the sign's ruler. A transit of Rahu over the sign lasts about a year and a half and sets a separate layer of restructuring. The houses the Sun falls into in a chart, and the planets it's linked to by aspect, specify which spheres of life sharpen during these periods.
How it manifests
In character — through diplomacy. A person with the Sun in Libra isn't inclined to direct pressure: their will works through accounting for the other.
In behavior — through accommodation. Here the will shows up as a readiness to look for a form acceptable to everyone.
In self-assertion — through relationships. The Sun in Libra proves itself by how well the alliance is built and measure kept.
What to watch
The strength is the ability to bring together and reconcile. Where diplomacy and a sense of balance are needed, the Sun in Libra works naturally.
The weak point is indecisiveness: deference to the other turns into difficulty where a firm "no" is needed.