Why do they have rayguns AND swords?

My Valentine's present arrived from Amazon yesterday.
Jill got me the DVD box set of all three Flash Gordon serials starring Buster Crabbe.
They are wonderful!
I watched the first four chapters of the 1936 original "Flash Gordon" last night.
As a kid, I spent many hours watching Flash Gordon on TV. Even in the immediate pre-"Star Wars" period of the early 1970s, the special effects on "Flash Gordon" seemed somewhat laughable. The thrilling action more than made up for a few sparkler-propelled rocketships, however, and I have loved Flash Gordon since I was about 9 or 10 years old.
I will be watching more Flash Gordon in the days to come.
Meanwhile, I will be pondering this question that arose last night as I watched:
Why do the warriors of Mongo use both rayguns AND swords?
If I had a raygun, I would simply shoot my combatant before they even got close enough to whack them with my sword. Perhaps that is why Ming the Merciless was doomed to fail in his attempt to conquer Earth?