1.  Who was Sahastraarjun? Sahastraarjun and Raavan.
 2.  Sahstraarjun and Parashuraam.

One day Sahstraarjun went to prey and came to Jamdagni Rishi's Aashram. Maharshi Jamdagni had the Kaamdhenu in his Aashram, so he entertained Raajaa and his army very well with it. When Arjun saw this glory of a Muni which was more than his own, he did not even ask for the divine cow, but he untied the cow and took it forcefully to Maahismatee Puree. The cow started crying. When they had gone, Parashuraam Jee came at the Aashram and heard the incident. He rushed after them taking His Pharasaa etc.

Sahastraarjun was about to enter his city that he saw Parashuraam Jee coming towards himself. He sent his 17 Akshauhinee army to fight with Him, but Parashuraam Jee killed all of them in a few moments. Then Sahastraarjun himself came to fight with Him. He took 500 bows together and aimed his arrows on Parashuraam Jee. But He cut all of them with His one arrow and then He cut his head too. Seeing this his 10,000 sons got frightened and ran away from there.