Is there a trigger for being able to kill the undead queen behind the castle boss? I remember doing it the first time I played this game, but this time I can't kill her for the Queens Flesh for some odd reason.
Also, holy shit level 100? That's some serious farming. I was ready to claw my own eyes out after doing enough HypGaol runs to hit certain stat minimums. Pretty much back where I was when I got annoyed and replayed DS2 the first time around. I think I am at the point of needing to gank the Spider to do anything new, unless I want to power farm chalice dungeons for some reason. I might farm the castle to try and get my Ludwigs up to +9, as the Strigoi Vampire things on the roof have a small chance of dropping the chunks for it.
Couple observations as a filthy casual:
Stats-
I totally echo what others have said here about getting 25 STR for Ludwigs and stopping there. Skill you can never have too much of, even if you are not good at Visceral attacks, because it affects so many other things including damage scaling on the best weapons in the main game. Get Arcane to at least 15 (Beast Roar and the weapon enchant are good), maybe 18 or 20 if you want to play around with the other spells. Get Vit to at least 20 and End to at least 22 (enough for the entire swing patter of Ludwigs plus one dodge). Blood Tinge is a waste and scales terribly, but the spear rapier combo weapon is fun for clearing trash. Beyond that, just dump skill and Vit.
Armor-
Basically, wear what looks cool and whatever resist matches the enemy you are tackling. In particular, Frenzy Resist is a big deal for engaging a couple of the nastier enemies in Nightmare or the area just outside the spider fight. Once you level to a certain point, the bulk of your physical defense is going to come from your raw level anyhow, so sweating a few defense points here is not worth it. If you are really good at countering and dodging, the Student and Knight sets are baller for all around resists. Armor is really about the most pointless gear in this entire game.
Weapons-
Ludwigs does everything and does it the best by the time you get it with the stats you should have. I know people swear by the whip, but its a lot easier just to flip into one hand mode when needed and stunlock shit the entire rest of the time. Seriously, I cannot believe they have not nerfed the piss out of this weapon by now. You can pretty much power through the first part of the game with the Axe and then throw it straight into the trash once you unlock Ludwigs. If you have a hardon for PVP, then yeah the big scythe rocks it, but otherwise Ludwigs will do everything you need for the entire run through. The few things I have seen be resistant to it have done down fast when you enchant it with the magic conch shell.
Martyr Fight-
His first stage is largely unable to be parried, aside from his generic sickle swing. Pretty much roll through the spells and stick and move. Stage two, when he starts dropping his sword, you need to bust out the gun and pop the weapon periodically. At this point, he can be parried rather easily, but you are better off just powering him down and backing off periodically for heals. He wastes a lot of time dropping that blade and charges you whenever you snipe it, so if you get a rhythm down of snipe-roll-switch-chop, this part is actually easier than the opening sequence. If you are at the point where you have the magic weapon boost conch shell, it helps a lot here but you need to be sneaky about casting it so he does not hit you with a big nuke.
Still vastly prefer DS2 and DS1 to this, but I am powering through it so I can complete the main game before Witcher 3 deteriorates my skills too much and I have to restart again.