Obviously there is a bit of trouble in translating weapon combat over to the anatomy of horses, particularly sword combat. Generally, I use a set of rules of the weapons in Equestria and attempt to form realistic fighting styles based on their range of motion in the show.

Swords: For pegasi, regular arming swords are easily used by gripping with the wing, as we have seen then do so. Longer two-handed weapons, however, are only available to unicorns, since wings cannot reach together and use a longsword or greatsword's leverage.

The problem arrives at mud ponies and their muddy hooves. Horseshoes are essential in fixing this. Earth ponies are able to use swords by attaching a horseshoe to the sword. The ends are each forged onto the quillons, while the vertex of the horseshoe's loop is a part of the pommel. This horseshoe then attaches onto the pony's hoof, or another another horseshoe the pony is wearing. Like the pegasi, they cannot use two handed weapons since three hooves is the minimum to walk and use hoof work.

When describing fights, despite the difference in anatomy, I simply keep the bladework more or less in tune with what is true in traditional combat. Where I see a need to modify the details, I add it, but for the most part, I would describe the techniques the same way I would describe this (action begins at 2:00):

Thoughts?

6028779
Not much on my end sorry, I mostly concentrated on how firearms would work for the ponies (skipping most types and going from matchlocks straight to metallic cartridge breech-loaders) . I think apart from mouth held swords and knives, spears and polearms would be the main weapon they would use because they can grip it with a single leg.

This sounds excellent to me.
I'd say the stronger the earth pony, the bigger the sword, however many hooves it takes.

6029217
To an extent, however longswords work on leverage, not strength. They require a second hand at the pommel to rotate the weapon and switch directions. The thing is, despite being able to use twice the strength, two handed swords aren't twice the weight. They're perfect for fighters who aren't particularly strong. For ponies, burly characters of immense strength would be better using spears and lances, since they can put the strength and weight of their body through the whole weapon in a charge.

6028881
What I don't like about mouth-held systems in stories is that it simply doesn't work. There's a very limited range of motion with the neck, meaning very little power can be generated in the strike.

Ah, I hadn't thought of that.
I suppose that makes sense.
How would crossbows be handled manually?

6029369
Crossbows are probably best strapped onto a foreleg, pointing toward the hoof (and the ground if they're standing on that leg). You're going to need some muzzle-activated trigger set up in such a way that brushing it to fire won't throw off the aim, and I'm not sure if it would be better to load it with the strength of the opposite hoof or the dexterity of the mouth. Or alternatively, what they offer over at least powder-based (as opposed to magical) firearms is the ability to be weilded by mouth whithout worrying about the recoil breaking teeth.

The trick with describing Equestrian weapons is that ponies aren't humanoid -- I know that's what this entire thread is about, but nobody's yet mentioned that the weapons themselves may be different. I've seen several stories featuring wingblades that strap to the leading edge of a pegasus's wings, or the battle saddles from Fallout: Equestria (as much as the common depictions of small arms don't work without resorting to magic) that strap a big gun or two and a reloading mechanism to the side of a pony and the trigger to the bit. Yeah, it makes it harder to directly use humans fighting as reference, but to my ear weapons designed for ponies rather than simply adapted ones can make it seem more realistic.

6029217
Perhaps the stronger ones can even train to be on the back legs for a two-hooved sword.

6028779
Swords are simply useless to the non-unicorn breeds. A pegasus wing, even if it can grip, is not the size and shape of a human hand. It is not meant to wield small handles. Earth ponies can only hope to use swords if it's a mouth-grip system, which is simply not as good as having 2 arms.

Unicorns, however, can wield swords better than humans. So you have a weapon which is deadly when used by unicorns, and clumsy when used by non-unicorns. You can say that's the reason why ponies in the show don't have swords.
6029368
But we're talking about pony necks and pony mouths. Not as good as 2 arms, but not as useless as a human head.

There are two basic questions you should answer before designing your weapons.

1) Do ponies have sort of hoof telekinesis which allows them to play piano, guitar and so on?
2) Do ponies use anthro-stance which have been shown to be practiced even in combat?

I see you have an answer for the first question, and it is "no". But this has a lot of consequences which lead to unicorns being no doubt superior because of huge advantage they get in everyday life by using simple telekinesis. Are you sure you need this?

7141512
A grip capable of fine manipulation and one that can keep hold of a weapon in combat aren't necessarily the same - especially if it's magical.

7141514
And again, you need a good reason to use this particular restriction because it looks complicated.

There are a few things to consider other than just taking various human weapons and trying to figure out how ponies could possibly use them. Like how they came to develop them - obviously unicorns and anypony who've seen them will develop the lance, but where did creatures without arms or sharp parts get the idea of slicing and chopping tools - a predator's claw?

Also to be considered is the context of where the weapons will be carried and used - many are more suited for the battlefield, others are more flexible. And ponies' differnces from humans affect such practical factors - they can wear long weapons more easily, but will generally struggle to conceal any unless they're one of the half of ponies who go clothed. (Indeed, more clothed societies may be quite associated with backstabbing, especially among unicorns who could draw a blade quickly. Of course, a treacorous unicorn could often just use a spell or magical blast...)

7142098
Somehow they did, because they have these tools in canon, so we should not bother about it or go for some heavily alternative universe where ponies did not use all the stuff from the series. IMHO the differences are not too big in this case because... how did humans developed their tools?

Wow, i forgot about this dueling and assasination stuff. Thanks.

7142365
Humans have arms suited for swinging and throwing (which also led us to ranged weapons). If ponies don't have such vhings, then any equivalent techs were probably a) copied off some other species and b) likely not so common.

7142388
They still use mouth and sometimes even tail. As for hoof grip, there's a spear sparring between Mighty Helm ponies, though it's quite weird. So ponies can swing with one leg while standind on the other three, and the question now is would this be better than straightforward ramming into the enemy and beating him down with bare hooves.