Mandalorians are some of the best warriors in the galaxy.  Rarely Force-sensitive, they don't trust Jedi or Sith, and when they ally with one it's usually Sith.  Some, such as Jango Fett, could kill Jedi easily.  It's certainly not good to be against one in either combat or their local games.
Sith, more great warriors, are equally dangerous.  They are secretive and, in the case of a Jen'ari, are better fighters than Mando'ade.  
It's a good thing the galaxy has never seen one who is both Jen'ari and Mand'alor ...good for the Jedi, that is.