Currently, I'm aiding Quillian Inkheart in writing a story about a super soldier Nightmare Moon created that does not like how Luna was forgiven for her crimes after the Return. One of the things I mentioned was that ponies shouldn't have spears or swords, and he responed with evidence from the show that ponies have spears, and stated that swords are even easier to explain.
However, I am a huge nerd. These explanations do not fly.
Consider the following images:
One here
Another over here
And the last one here.
Notice something?
The guards aren't holding those spears, they're balancing them in the crooks of the forelegs. That's the only way they have of holding them. If they got into a fight, those spears would be useless. Moreover, spears are supposed to be stabbing weapons. You have to be able to wind back and push forwards, but that's a range of motion very far away from what a pony can do unless your story works on cartoon physics. Which is fine for you, but us realistic folk are left out in the cold. But of course, we aren't helpless. We still have the single coolest weapon left, the sword!
See here, another one here, and OHMYGOSHWHATISTHISHOLYCRAPILOVESWORDS.
Ahem.
( Okay, fine, just one more)
But if you could possible contain you enthusiasm for a moment, you would notice a large problem with the way these ponies are holding their swords. Actually , several problems, nearly all of which can be seen in this one one image here
The first is that in order to fight properly, you need to be able to see both your sword and you opponent. Don't believe me? Try this out for a second. Go pour a bowl of cereal, and eat it while looking at the ceiling. Then pretend the bowl of cereal is moving around and trying to kill you. Harder than it looks, yes?
The second problem is one of range. You can only defend on area with your sword: either the left, or the right, depending on which way you chose to pick up the sword. Choose carefully, because whichever one you chose, the entire other half of your body is exposed. You can turn to block it, certainly, but since you are a pony you're built much more laterally than a human and therefore aren't made for sudden turns. Getting on your opponents blind side is so much easier than defending your own that it makes wielding a sword far more dangerous to is wielder than anypony else.
The third problem is comparatively small: Mouths can't grip things as well as hands. The muscles simply aren't as strong, the mouth cannot competently encircle the sword, and eventually the shocks from the impact will knock out your teeth. Ponies would never invent swords, and the only ones who could use them are unicorns. Ponies might start carrying daggers and smaller blades, perhaps attacked to their forelegs, but wielding larger melee weapons is a biological impossibility.

5293288

Seems legit to me.

I've often thought that perhaps a pony would use a smaller blade attached to their foreleg.

5293597 Like some kind of wolverine/dagger thing.