That's very true Hulan, the basic style of FFXIV was modelled after real life medieval weaponry and armour. However we aren't on Earth, we're on Eorzea, and while these weapons serve as a very solid basis for design and realism on a stock-standard character, it only makes sense that once you transcend the power of something like a primal, you would obtain such an item that befits a warrior strong enough to actually take one down.

I highly doubt that people who play MMOs play them for the life-like realism of medieval England, or at least any substantial portion of them. It's important to always consider the fact that we're dealing with massive monsters, interdimensional creatures and magic here, it's bound to separate itself from Earth history at some point.