This adds a circular sector:
radius = .2;
arc = Table[
origin + radius*Normalize[t v1 + (1 - t) v2 - origin], {t, 0, 1,
1/10}];
Graphics3D[{Red, Arrow[{origin, v1}], Black, Arrow[{origin, v2}],
Arrow[Reverse@arc], Opacity[.3], Polygon[Append[arc, origin]]},
Axes -> True, Boxed -> True]