I don't get the one weapon vs. another weapon mentality. You can carry more than one weapon and have the option to purchase more weapon slots. You weigh your arsenal with the type of armor you currently equip since you cannot readily change armor like you can change weapons. You also have the option of checking floors to determine the element and mob types you will be encountering in addition to planning how to use the terrain in the most effective and fun way possible.
It's like washing clothes. If you toss ALL the dirty laundry into the washing machine, add bleach, detergent and hot water...you come out looking like a noob. If you take the time to sort and add the appropriate accouterments...you will always be dressed for success.
The one weapon to rule them all is no one blade, gun or armor set. In terms of weapons, the knight herself is the total package. If you set your knight to be great on only one path, that leaves your knight vulnerable. Achilles was a legendary warrior of no equal. However he had one weak spot. Do you have your weak spots covered?
People are cheap and don't want to buy extra weapon slots. With only two slots, you have to be a lot more picky and rather than realize they're handicapping themselves, they blame the available weapons for not offering an option to instantly kill everything on the first hit.
It's like having 4 finals at the end of the semester, deciding to only study for two of them because it's a lot of work to be prepared for all 4, then blaming the professors at your university when you fail two classes because those classes required you to have knowledge that you didn't gain in the two classes you passed.