system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why did so many cavalries use curved swords (sabers, scimitars, etc)? What advantage do they give?
gpt
A generic straight sword is good at both stabbing and slashing, can be used two handed for extra power, and can be used against opponents on either side of you.

On a horse, you are basically just slashing, one handed, to one side.  A curved sword is better at slashing, at the expense of stabbing and being useful in both directions, but those are less important on a horse.