>>96154189
The inspiration is likely the Jackson movies, but justifying it with "elves dumb and don't innovate" is equally dumb. Especially since adding a handguard is not some secret super tech that only the Europeans figured out. While traditions and custom should play a role, there should also be practical considerations for why they never bothered with them to begin with, that also apply to the current time of whatever setting.
Properly armored hands and arms, a fighting style that doesn't really extend the weapon hand much and doesn't really care about parrying and binding enemy blades, or combining them with shields. Being civilian weapons created for easy wear first and foremost, and being secondary weapons worn while the elf uses a bow, a spear (plus shield) or something else primarily. Also, not just convenience of wear, but it makes them quicker and easier to draw. It's not like a handguard is always a benefit with no drawbacks that everyone should have done if they weren't dumb dummies.