I've just defeated Quelaag, and I'm SL34, but I'm not sure what weapon I should use for Sen's Fortress. Up until now, I've been using a Battle Axe +4, which I don't want to use anymore since it's so slow and unwieldy. I have 16 strength and 13 dexterity, and I'm not sure if I should use a falchion, and eventually get a Quelaag Furysword, or a longsword, which seems more versatile. Which weapon do you think I should use?

Use whatever you think feels good. I use Quelaag a lot, but keep an uchigatana for tight corridors and some bosses who shrugs off fire.

Most weapons are good when upgraded, just pick one with a moveset you like.

Battle Axe is pretty good all round, it really depends on your build, personally I found the lightning spear to be good and judging by the people i've invaded, others seem to agree, you get it in Sens Fortress off a mimic (chest monster). Lightning seems to be pretty effective against most of the enemies in the game.

I went with a lightning claymore and it has served me well up to Ornstein and Smough on NG+. You get the claymore on the bridge where the dragon is breathing fire early in the game. Like a previous poster said, lightning is definitely very effective.

It really depends on which stat you intend of making your primary.  Strength lets you take advantage of the larger, heavier weapons as well as great shields while dex requires you to be a lot more nimble.  Don't forget also that both Int and Faith are viable primary stats even if you want to be a melee character due to the existence of divine and magic ascensions for weapons.
 
And of course, all this is rendered moot by the strength of weapons ascended to lightning due to both their superb fixed damage values which out pace any weapons that scale off a stat currently as well as the lack of shields that block lightning at a high percentage.  A patch should be out soon to balance that though, along with a lot of other stuff.
 
Note that there is a lightning spear right in Sens Fortress which can last you for the rest of the game if upgraded.

It really depends on which stat you intend of making your primary.  Strength lets you take advantage of the larger, heavier weapons as well as great shields while dex requires you to be a lot more nimble.  Don't forget also that both Int and Faith are viable primary stats even if you want to be a melee character due to the existence of divine and magic ascensions for weapons.  And of course, all this is rendered moot by the strength of weapons ascended to lightning due to both their superb fixed damage values which out pace any weapons that scale off a stat currently as well as the lack of shields that block lightning at a high percentage.  A patch should be out soon to balance that though, along with a lot of other stuff.  Note that there is a lightning spear right in Sens Fortress which can last you for the rest of the game if upgraded.

You'll pick up a Lightning Spear halfway through Sen's Fortress that will be stronger than anything you'll be able to quickly make.

You'll pick up a Lightning Spear halfway through Sen's Fortress that will be stronger than anything you'll be able to quickly make.

@Spoonman671 said:

You'll pick up a Lightning Spear halfway through Sen's Fortress that will be stronger than anything you'll be able to quickly make.

Speaking of lighting. Where am I able to upgrade stuff to use lighting? 

@The_Laughing_Man said:

@Spoonman671 said:

You'll pick up a Lightning Spear halfway through Sen's Fortress that will be stronger than anything you'll be able to quickly make.

Speaking of lighting. Where am I able to upgrade stuff to use lighting? 

I think you have to go to the Giant Blacksmith in Anor Londo, which is the next location after you make it through Sen's Fortress.

Lightning weapons are very good if you don't want to dump a ton of points into strength or dexterity. Really any weapon you like will make a good lightning weapon. Personally I chose the flamberge, which is basically a cooler looking version of the claymore that causes bleeding also, though the claymore does a tiny bit more damage. Claymore base damage is 103, flamberge is 100 + 300 bleed points. The movesets and attack speeds for both are the same except for the strong attack, where the claymore does a thrust and the flamberge does a downward slash.

Another very good choice is the uchigatana, which is a fast falchion-type weapon with base dmg 90 that also causes 300 bleed points. It would probably be the best all-around choice except for the fact it has very low durability compared to most weapons- 80 durability. So you can't go for too long without repairing it, though that's not really a big problem in Dark Souls since you don't go for super long periods of time without being at bonfires, either through dying or just playing. I plan on making a lightning version of this weapon also. Anything that you upgrade to lightning +4 will tear up enemies as long as it's not a piece of crap to begin with.

If you really want to do a LOT of damage, or are very PVP focused, Queelag's Furysword is one of your best choices, but you will need to put points into dexterity and carry around a lot of humanity because the damage scales with both. Lightning weapons don't scale at all. So scaling weapons won't outdamage lightning weapons initially but if you plan on getting to a very high level and want something to last you long-term get a weapon such as Queelag's that scales (there are other good ones but I don't know as much about them)

I've been using Astora's Straight Sword from the beginning and it's been exceedingly kind to me. it has a swing and thrust so it's great for nearly all situations. it also scales pretty well with Str, Dex and Faith so it's a good weapon for Priests.

and it's holy so you don't have to upgrade a weapon to go into the catacombs

I will have to find another weapon eventually though since it can't pass +5 but at 80/80/0/0 at +0 to 120/120/0/0 at +5 it should suffice for at least some time.

You'll need the Master key. From Firelink, take the elevator down to New Londo. Once there, as you head down the elevator-tower. Walk out where you find some crying zombies and take a right to another entrance into the same tower you climb a circular stairs and there's a gate you can open with the Master key. pick up any goodies and cross the precariously thin bridge take a left and you'll find a rotting dragon corpse with some human corpses next to it, these have items Astora's Straight Sword, Dragon Crest Shield and a Consumable soul. The dragon will wake up when you pick up any of these items and Regurgitate it's stomach-rot causing Poison. quickly grab it all and get out, Mind it's claw as you get away from him... later you can come back and put it out of it's misery with some spells or arrows from the edge of it's sick-pool as it can't reach you and it won't swipe at you, for some more free souls and a Dragon scale.

Today I have made my very first demon waepon, which is Quelaag Fury Sword. At first I found it to be weak, but I upgraded it to +5 and i must say, it's amazing! Even now, on SL 50 it's so much better than lightning spear from anor londo, and it scales, which lightning weapon can't do, so it will keep getting better and better. The only issue I noticed so far are fire resist enemies, but there aren't many of them and I have still lightning spear to deal with them, so they aren't a serious problem.

I have also used a black knight sword +2, though it was too slow for me, its damage was pretty high.

So as far as I am concerned, fury sword is the best weapon I had so far and it scales with both stats and humanity, but this second thing has also a downside which can be frustrating if I lose all the humanity i carry around :(

I fought the mimic in Sen's but it fell down the elevator shaft, so no lightning spear for me :(. Are there any good weapons I can find in the near future, or should I stick with my longsword+9?

+5 Ligtning Zweihander
357 Base Damage
364 Lightning Damage 

This sword is a beast, it is slow to swing, but if you connect you essentially throw your opponents around.  It has a great replacement for your standard strong attack as well, you swing with a downward arc that knocks enemies down on the floor. This lets you to be cheap so you can do it over and over again without letting your enemies get back up.

I can really recommend a 5+ Chaos Great Scythe. You don't need any big stats for it to be good and it has some really great sweeps that will hit anything in front of you.

Since I've found the Great Scythe I haven't found a weapon that's anywhere close to it.

@gosukiller said:

I can really recommend a 5+ Chaos Great Scythe. You don't need any big stats for it to be good and it has some really great sweeps that will hit anything in front of you.

Since I've found the Great Scythe I haven't found a weapon that's anywhere close to it.

I recommend this as well. It + pyromancy is all I used on my previous character.

In sen's fortress you can find the lightning spear. That weapon served me well until i made Quelaag's Fury Sword.

Where do you get the Great Scythe?

Redirect the boulders rolling down the multi level stair set in Sen's Fortress so you can safely get to the bottom. Take a left at the bottom of the stairs and attack the treasure chest. If you have to gain ground, back out of the hall so that he doesn;t do something stupid and get onto the elevator and die on the spikes above.

Kill mimic, get the lightning spear. upgrade the lightning spear.