Alright, I've spent all day gathering some knowledge for you all regarding the weapon based matchmaking. I've been trolling around the memory of the game to see how and when it changes.
Why not post this to the sticky? Hardly anyone reads the sticky, and even fewer reread new comments.
I'd still refer to the sticky regarding how your "weapon upgrade level" affects matchmaking, as this post is only for what affects the upgrade level.
Put simply, your upgrade level is determined by any item you have ever possessed that would show up in the Reinforce Weapon or Modify Equipment menus at the blacksmith and pyromancers. Exception: Dark Hand
Getting rid of an item by any means
WILL NOT decrease your characters weapon upgrade level.
So this means the following things DO affect your upgrade level:
• Bows/Crossbows
• Melee Weapons
• Shields
• Pyromancer Flames
• Dark Hand
And the following things DO NOT affect your upgrade level:
• Reinforcing your estus flask
• Armor
• Spells
• Rings
• Staves and Talismans
• Consumables and Upgrade materials
• Number of dung pies fed to Frampt, etc.
Note: Going forward, I will be denoting WL (Weapon level) when talking about the internal stat DSR uses to track your highest weapon upgrade level from 0-15
So what is your WL?
A simple rule of thumb is that if you fully upgrade a weapon, you will be at WL15. Refer to the upgrade chart:
http://image.ibb.co/i9bi2c/dark_souls_upgrade_guide.jpg
If you have an item from the normal tree, its WL is the minimum number of times it needed to be to be reinforced to get to that tier starting at WL0. So the lightning spear +0 from sen's fortress, that's a WL10 weapon. A chaos zweihander +5, that's WL15. Exception: Boss weapons at +0 will start at WL5 even if the normal weapon used to make it was WL10. The character will still remain WL10 after making the boss weapon but this shouldn't affect characters who have the boss weapon muled to them.
If you have an item from either the boss, demon, dragon, or unique categories, it will start at WL5 immediately and increase by 2 each time you reinforce it. The exception are shields in these categories (Havel's, Stone) which will start at WL0 and will increase by 3 per reinforcement (leaving it at WL15 when fully upgraded). Even though the Dark Hand can't be upgraded, it counts as a WL5 weapon.
The pyromancy flame starts at WL0 and increases a level each time it is improved. It is WL15 fully upgraded and unascended. Every upgrade level of the ascended pyromancy flame counts as a WL15 weapon as well.
What does this mean? For the endgame, it's meaningless, but it can affect your Coop and PvP experience as you go through the game. You should decide which group you'd like to be in. The "
Not as many people but with twinks that are far more optimized than I am" group or the
"More people and more twinks but at least it's a more even playing ground" one. If you want to be in the first, just play as normal and pick up anything you want knowing that picking up the wrong item at the wrong time can push you into a smaller matchmaking pool prematurely.
For everyone else, here are some tips on not accidentally bloating your upgrade level until you're ready.
1. Once you go black k***t, you never go back to invading unupgraded hosts . Just avoid black k***ts, as all their weapons will immediately bump you to WL5.
2. Let the poor thing sleep, don't take the Astora Straight Sword from the undead dragon in valley of drakes or the lightning spear from the mimic in Sen's fortress.
3. A tail of two dragons. Don't cut tails unless you REALLY need the weapon. This primarily goes for the drake sword or gaping dragon, both optional tail cuts you can postpone as long as you want. Gargoyle axe is fine, it's in the normal upgrade path. By the time you reach priscilla/stone dragon/seath/kalameet you should be fine with a tailcut weapon (unless YOU are the twink).
4. Know what you're signing up for. You get the gravelord sword upon entering the gravelord covenant and a dark hand from the darkwraith covenant, so be mindful of that.
5. When in doubt, refer to
Rare Weapons - Dark Souls Wiki for any other potential gotchas that you may stumble across and you should be good.
It's unfortunate, but it's not the end of the world. You should be keeping backups anyway, they can help if you catch yourself picking up a wrong item.
There may be more exceptions than what I've thought of but I'm willing to take testing suggestions or answer any questions in the comments.
Edit: Added note regarding Boss weapons, and fixed WL for lightning spear
TL;DR:
[View formatted table]
Weapon WL
Weapons and Shields that have 15 ranks TOTAL WL0, +WL1 per rank
Weapons that have 5 ranks TOTAL WL5, +WL2 per rank
Shields that have 5 ranks TOTAL WL0, +WL3 per rank
Dark Hand WL5
Pyromancy Hand WL0, +WL1 per upgrade
Ascended Pyromancy Hand WL15, no change per upgrade