I've read the first 24 issues of JUMBO COMICS, and so have noticed that Sheena's not much of a hand-to-hand fighter during this period, relying almost entirely on weapons like knife and spear. In the story from issue #20, though, Sheena meets a female foe who outclasses her in sheer strength: Keela the Ape Queen, who as the captions say, can life a six-hundred-pound gorilla as if he was a mere fifty.
When Keela tries to steal Bob, the women come to blows. Sheena suddenly acquires at least one jui-jitsu move-- possibly taught her by her "mate?"-- which spells doom for the super-strong gorilla-girl.
Meanwhile, in issue #17, time-traveler Stuart Taylor and his pals jaunt back to the era of Alexander the Great. History-books won't tell you how Alexander's reign was endangered by a tribe of Amazons-- how negligent!