I see it brought up in a lot of askhistorians answers that spears/pikes/axes/maces/hammers/cutlasses/etc. were all much easier for a person to learn how to use compared to a sword. What is the basis for these claims? Are there primary sources that support any of them?
The answer is going to depend on the era, and on which theater of conflict you are talking about. Perhaps you can specialize your question, or give examples of these answers you were specifically looking at?