It was the followers of Armadyl who enjoyed the greatsword so much, in defiance of the bows that were more the more traditional choice. They said that it reminded them of the legend of the godsword, and would lament not knowing the secrets of forging one, as it would be quite useful against the godeater, Kuldra, and her call for humanity’s death.
Sadly for the villagers, the art of godsword creation was never discovered, so they turned to steel instead. Whilst significantly less flashy, and almost certainly not going to terrify any deities, a steel sword will do significant damage to anything not divinely attuned.