Du Fu (or Tu Fu in Wade-Giles romanization), was one of China’s most famous poets, from the Tang Dynasty. His dates are c. 712-770. There are lots of sites to explore, for example:http://www.chinese-poems.com/du.html
I think there are probably plenty of sites that mention Li Jinglin as well, if you search the name on google.com.
Barbara Davis translates the calligraphic endorsement as, “The Sword’s Brightness Reaches the Clouds.” Here’s her biographical synopsis:
General Li Fangchen, also known as Li Jinglin, (1885-1931) was from Zaoqian, Hebei Province. A career military man until his forties, he later helped to establish a martial arts center in Nanjing and then served as its assistant director. Li came to Shanghai in 1927. He had a life-long interest in the martial arts and was particularly skilled at sword He arranged a sword set he titled ‘Wudang Sword’ and also wrote an inscription for Chen Weiming’s Questions and Answers on Taijiquan. (Barbara Davis, trans., Chen Weiming: Taiji Sword and Other Writings, p. 3)