If your pony isn’t a unicorn, DON’T EVER MAKE THEM USE A SWORD. THAT INCLUDES PEGASUS.
No seriously, unless you have a mouth guard on, DON’T. Do you want your character have broken teeth, broken wings, fractured bones, stretch marks and rough gums?
Mind I suggest using pole swords, long-handled knifes, spears, long handle chinese weapons, maces, warhammers, staves, wing blades, and ANYTHING with long handles instead?
In case people didn’t know, horses/ponies have a gap that has no teeth in it between their front row of teeth and their back molar-ish teeth. That’s usually where the bit goes on a bridle (the face-harness thing that the reins attach to so you can lead/steer the horse). So if your pony is carrying any weapons in their mouth, that’s where it’s going to end up resting.
I forgot about that! (Ironically since I look at horse skeleton systems a lot)
But still, before you do, check if your pony if has enough experience too and safety! Like a mouth guard or not easy to get sick as your pony will be swinging their head a lot!
I still recommend using weapons with long handles because you’re limiting your pony’s movement with only a few ways to attack and often making your pony vulnerable at their backs. Also generally more weaker slashes over time.
I admit though, swords are great for tanky characters.