I have a few ideas that I feel would add a lot of variety to the game. To preface this I want to make clear that I am suggesting new weapon types, not new weapons. What I mean by that is that there should be at least 4 weapons for each of these suggestions (one each with normal, shadow, elemental, and one with piercing damage).

Idea #1: (Sniper) Rifles

The rifle would have a range double that of a standard gun. It would only fire one shot before having to be reloaded (like a bolt action rifle). This would be nice because it would allow a gunner to really hit enemies from a farther distance. The damage should also be increased anywhere from 50-75% over handguns, as rifles do hit much harder than a handgun in real life.(just an initial estimation). A major drawback would be the reloading time. You would have to choose wisely when to use a rifle because there would be a several second vulnerability period after each and every shot. I feel that this period of vulnerability caused by the reload would help to make it a more balanced weapon because it wouldn't be fair to have a gun with a really long reach without a drawback.

Idea #2: Knives

Not every blade-wielding warrior over the years has carried a sword; knives are handy weapons too! Knives would be held in each hand while the character was wielding them. Knives would have an increased attack speed over regular swords, but would deal less damage and have a shorter reach.

Idea #3: Shotguns

I know this has been suggested elsewhere, but because I love it so much I wanted to mention it here too. Shotguns in my vision would be able to fire two shots before being reloaded (like a double-barrel shotgun). I would also recommend a 1.5 second refractory period before firing the second shot due to the pump action required. The range of a shotgun would be approximately 50-75% less than a regular handgun. I think that the projectiles would be similar to buckshot in that a lot of small bullets shoot out in a single shot. Because of the chance for landing multiple hits in a single shot, I DO NOT recommend that the shotgun be given a damage increase. On that note, because of the the time required to pump between shots, and the reload time, that it doesn't receive LESS power than a regular handgun.

As you can tell, these are simply rough outlines for some ideas that I've have running through my head for quite a while now. Please feel free to make suggestions to idea 1,2, or 3.