This means that the servant was watching for enemies while guarding at the city wall. Alternate translation: "who was guarding" or "who was guarding at the city wall" (See: [[rc://en/ta/man/jit/figs-idiom]])
Here the servant looking up at something is spoken of as if he lifted up his eyes. Alternate translation: "looked up" (See: [[rc://en/ta/man/jit/figs-metaphor]])