Vader blocks all blaster fire, while slashing and using the Force all in concert, that is not a weak showing. That's Vader multi-tasking.
It's clear by SW cannon that Dooku is Maul's superior. Maul has flashier attacks, but flashy attacks do not win alone. Dooku's also a superior duelist; not just in the Force compared to Maul, he doesn't rely of flash as much, but the skill-set is there. He matched Yoda in epII with sabers. Yoda > Maul.