Clowns are meant to liven up the atmosphere at the circus, and then, perhaps they've got a knack for juggling balls or throwing knives with deadly accuracy.
You can't go wrong with a nickname, and Tirado's moniker "Clown" surely meant he had some incredible skill with throwing knives.
Clown's skills were far too specialized; Gao Yang was definitely outmatched in this respect—this was no contest. He could run but couldn't climb, let alone throw knives, and Satan didn't have anyone with that kind of talent, either.
Throwing knives might have their use in special situations, but they're not something you'd want to rely on in battle. However, climbing barehanded couldn't be dismissed as useless. Otherwise, why would counter-terrorism forces and those specializing in urban and indoor combat spend so much time diligently practicing climbing and rappelling?