General

@metallicgryffon:
If you ever want to rid of your soul weapon greatness that's attached to your weapon, talk to the murgoth wizard guy whatever (he's in leafre, hene, etc.)

btw: You don't GET a soul weapon. You get an attachment that's used exactly the same as how a neb or scroll works.
Get a SOUL ENCHANTER. Google that on how to get it. (I bought mine, you can also get it from drops in the soul weapon guy's dungeon (murgoth i think)
Once you get the soul enchanter, apply it to your weapon and then it will turn into a soul weapon. From there, use the comment above me to guide you.

Stage 1: Make your weapon a soul weapon.

When your weapon becomes Soul Weapon, it drains souls from monsters. Just like Demon slayer, when you kill monsters, you see draining effect.
You get a new "Soul bar", it rises when you drain souls, and when it reaches 1000 (max), you get +10 att/m.att.

Stage 2: Get a soul into your weapon.

After getting 10 shards of a specific boss, you can convert it into an Orb (Use Item) with the picture of the boss on it.
Use the Orb (like a scroll) on a weapon, and the weapon gets a bonus stat (for example, +4 DEX, or +4 attack, things like that), and the attack bonus may rise (10/15/20)
PLUS, when the bar is charged to 200, you can use a new skill, summon the soul of the boss/monster in your weapon, to activate a buff. or an attack.

For example, after getting an Arkarium Orb, I used it on my staff.
Now, when the bar reaches 1000 souls, I get +20 m.att (instead of 10).
Also, at the price of 200 souls, I can summon Arkarium, to use a powerful poisonous skill that causes monsters Damage over Time.

can an item-locked weapon become a soul weapon? my gear is always locked so Im wondering about it

hot key to soul if you plan on using it. It's in ur beginners slot

Having a soul weapon gives you 10 ATT.
In addition to that, you can get a Soul Orb which gives you stats/buffs aswell.