ball and chain mace. yep, thats about it, maybe a scythe.

throwing weapons.

shards
stars
or crafted granades.

or ability to use the Bear Traps as weapons.

Well...you can already carry a Beartrap and drop it somewhere else...actually very fun

Oh forgot one more thing!

A Lance - Jousting!

we already have horse mounted combat so how about a unique lance with quest similar to Auriels Bow quest.

DawnBreaker.

Um... It's in Skyrim already. Not sure why we'd need to include it in a new DLC...

DawnFang/DuskFang*

Fails and other Chain based weapons.
Polearms (halbreds, Pole Axes, War Scyths)
Spears (both 1 and 2 handed)
Bastard Swords and Hand and half Swords
the ability to throw weapons
Fist weapons( This would allow for unarmed to viable with out adding in a new perk tree)
Alchemical Grenades ( poisonous gas, flammable gas, knockout gas, smoke)

leather armor like in Oblivion, with a cloak.

Deffintly loving the idea now, it would fit my Adventuer/Treasure Hunter character. However maybe it could fit in the archery tree, even though it it doesn't fit in it. Also you should have to find Gun Powder packets.

I was thinking a string bikini for the ladies and a man thong for the men.

Hand Cannon is a Range Weapon and should be effected by Archery Perks.. As to get one, you can only get one and the cannon cannot be made. A Dwarven Hand Cannon should be found in some sort of hidden part of Blackreach where a certain Dwarven Bot of some kind is using it. To get ammo, look for the plans of it and learn how to make. The ammo should require coal, steel, and dwarven. Coal can be mined in the area where you get the cannon and can be found on certain Dwarven enemies/machines. Also, the ability to make Dwarven Satchels should come with this. Dwarven Satchels were used in Tribunal to blow up rocks blocking up the path so my idea would be using coal and leather to make the satchel then you can place it. Note: It'll blow up in 5 seconds once placed.

For the story however I think there is a Dwemmer expert who has bean studying these ruins for years, ( could be that one from Markarth) he states that he came across a Dwarven mechanism that is unlike thing he has sean. He doesn't not know where it is located but has idea where it might be. You travel to a Dawvenn Ruin, that has a Explorer who was looking for the Hand Cannon. After reading a note dropped by him, it reads that him and two other's are in diffeerent ruins who have located keys to a sector of Blackreach. After getting these keys, you go to blackreach, insert the key's. After walking in and search some, a Dawven Centourin Master attacks.
A little long, but for a powerfull weapon like this it should have a powerful journey.

Nah. There shouldn't be a quest for the Dwarven Hand Cannon. It should be extremely hidden.. My idea is, the hidden part of Blackreach will eventually lead to another huge area that is even deeper into the earth, than Blackreach.. This deeper area would be smaller than Blackreach but is like a set of Dwarven Towers built with bridges to each one.. Cause below there is lava.. The Hand Cannon should be hidden somewhere in here and there should be a few corpses of treasure hunters that tried to find it before.. They'll have notes on it.

Also, Calcemo (I think that is his name) will offer you 10,000 Gold Pieces for the Hand Cannon is you find it and decided to sell it to him.

~Edit~

The area should have Falmers and Dwarven enemies... There will be a special guardian for the cannon... I want this now cause well... I wanna Fus Ro Dah some Falmers into de' lava.

it would be brilliant to fire multiple arrows at once, maybe as a burst fire or as a concentrated aimed shot. It would be cool to have some kind of grappling hook or rope arrow like in dark messiah. its a shame you can't enchant skulls with magic??? then again that might be a little oTT.

also why cant i make a ring of summon skeleton? i am pretty sure you could in morrowind

Throwing Knives

Yeah maybe something like a double-barrelled crossbow or dual wielding bows would be cool

Badass new robes. Unique Spellsword light armor.

More spells. Maybe craftable/enchantable staffs?

Although hiding item's would be sweet, but someone would eventuly find it and ruin the fun in it.I'm also sure Bethesda wouldn't want to hide it extremly well to people can enjoy it.

You can FUS RO DA followers into the lava of the Aetherium forge
It is the only way to take care of Mjoll for good

just say medieval gun we all know its a gun and if im honest it wud ruin the game it just doesn't belong in the elder scrolls, its not the fact i think it'll be overpowered i just dont like the idea of it in an elder scrolls game. Play fallout if u want a bethesda rpg with guns. Also the idea of putting it in the archery perk tree is a horrible idea

Ice Armor from Bloodmoon would be amazing. Daedric Crescent would be a welcome return. They could make it so it would come apart in the middle so it would work with dual wielding.

Bring back everything from oblivion and morrowind, remastered.

Also bring back a lot of spells.

if only we could have that haha