Sorry for disappointing you, the name is after Uesugi Kenshin, He was one of the most powerful lords of the Sengoku period. While chiefly remembered for his prowess on the battlefield Kenshin is famed for his honourable conduct, his military expertise, a long-standing rivalry with Takeda Shingen.
All Sengoku yoyos are based on real characters relevant in the Sengoku era, the character you like, Rorouni Kenshin is fictional and is from the Meiji restoration era, much later than Sengoku. 