What kind of medicine is better for weak legs depends on what causes it. If the weakness is caused by deficiency of qi and blood, you should take Chinese medicines and pCms that replenish qi and nourish blood. The main proprietary Chinese medicines are Ginseng Astragalus and Fructus Schisandrae, Tonifying the Middle Jiaoqi Pill, and Gui Spleen Pill. If the weakness of legs is caused by kidney deficiency, Chinese medicines for tonifying kidney should be taken, such as Kidney Qi Pill and Kidney Treasure Tablet. If the weakness is caused by calcium deficiency, you can take calcium tablets, such as Calcium Carbonate D3 tablets or Calcium Gluconate.