The anointed one was still a new vampire the master was training him to rule if he should die. But the master died so soon he didn't get to fully teach the anointed one much so it isn't his fault he was weak. It be like telling a kid he will learn karate and be the next bruce lee but than only teach him what the karate kid knows and tell him to fight Chuck Norris.
I STILL HAVE ONE MORE SEASON OF ANGEL TO WATCH BUT IM STILL NOT OVER THE FACT THAT THERES NO MORE BUFFY