My knees buckle and feels weak a lot too. would a knee brace help stop my knee giving out?

Unlikely: Knee buckling/weakness is not a sign of knee problems. The knee is naturally designed to buckle/bend. The muscles and nerves that control the muscles keep the leg straight at the knee. Braces do not replace or improve the muscles or nerves. Without a specific knee injury, knee swelling, knee locking, this problem is unlikely a knee pathology and therefore, a knee brace will not help.