I'll update this thread with new information as I find it. You can help by directing me to new information I haven't found yet.
The Official TOH Site
More TOH information
Article from Eurogamer
Interview from Gamespot
Interview (Oct 23rd)
Patch Details and Holy Moonlight Sword teaser
"Your message contains too many URLs. The maximum number of URLs allowed is 10."
More demo footage:
Official trailer (English)
Demo gameplay video #1
Demo gameplay video #2
Video footage of the "buzz saw" weapon
New weapons confirmed so far:
- "Bloodshed Hammer" - real name unknown, translated from the Famitsu scans. Supposedly a str/blt weapon, starts as a mace and is powered up by stabbing yourself with it.
- Holy Moonlight Sword - The iconic Moonlight Greatsword returns in its full glory for the DLC. Little information exists for this weapon outside one screenshot in the Famitsu article, and a brief mention about "wielding its mysterious power" in the Playstation blog patch details article.
- "rocket hammer" - real name unknown, was used in the demo by an NPC hunter. It's basically a fire-infused, rocket powered hammer. Trick mode appears to boost the next attack with jet propulsion.
- "burial saw" - real name unknown. It's the Burial Blade's blade, but folds in half like a Saw weapon instead of converting to a scythe.
- "Beast Cleaver" - real name unknown (to me, unless you can read japanese), was usable in the demo. A large, machete-like heavy weapon with slow but powerful swings. Trick mode unzips the weapon like the Threaded Cane, allowing for preposterously long range attacks that have knockdown, but are slow. Requirements are 15 Strength and 15 Skill, has very high strength scaling but skill scaling appears to be minimal (E rating skill, may be acceptable with high base damage).
- Saw Mill - Starts as a mace, trick mode uses the club as a hilt for a giant spinning motorized saw blade. Stat requirements are 16 strength and 12 skill. At +8, its scaling is A str, E skl, and B arc, with 167 base physical damage and +233 from a combined 24 strength and 20 skill. Mace form is pretty basic, saw form packs tons of decently fast multi-hit attacks with one that literally just keeps spinning until you let go of the button or run out of stamina.
- Simon's Bowblade - was usable in the demo. Starts as a slightly wavy longsword, converts into a mainhand bow in trick mode. Stat requirements are 8 Strength, 15 Skill, and 9 Arcane. When a bow, fires arrows that cost quicksilver bullets. Charged heavy arrow attacks are able to put enemies into a backstabbable state from long range. At +8, the weapon had 131 base physical damage with E Strength scaling and B Skill scaling, and 90 base arcane damage with C Arcane scaling. With 20 Strength, 25 Skill, and 13 Arcane, it got +161 physical AR and +7 arcane AR.
- "war pick" - real name unknown. A weapon that appears to start out as a spear-like stabbing weapon, and converts to a two handed warpick-like weapon in trick mode.
- "(unknown sword)" - real name unknown. Real anything unknown, really. Can be seen on the poster art for the expansion. Looks similar to a Reiterpallash in a Chikage sheath.
- "gatling gun" - a new firearm revealed in the Famitsu article scans. It's a "portable" gatling gun held in the left hand.
- "new gun" - real name unknown. A left-hand rifle that fires like a real rifle instead of a shotgun. Was used by an NPC summon in the demo.
- "mirror shield" - real name unknown. A shield for the left hand, said in interviews to be excellent at blocking arcane damage. No, it's not connected to the sword shown in the trailer, that sword is Simon's Bowblade in untricked mode.
- "Galasha's Fist" - translation of name from Japanese. Needs 7 Strength and 9 Skill to wield, at +8 has 116 base physical AR with A Strength scaling giving it +36 off 20 Strength. It supposedly allows for melee-range parrying without spending bullets.
New items confirmed so far:
- Blacksky Eye - Was usable in the demo by the "Mensis Scholar" build, but I couldn't find any footage of it actually being used. Fires a single, small arcane projectile at the targeted enemy. Quicksilver bullet cost unknown.
- "sticky grenade(?)" - A device you drop behind you, which then explodes after a short time. Seems to have high arcane scaling.
New mechanics confirmed so far:
- "beast mode" - seen in trailer at 1:12 to 1:15. Not certain whether this is a further stage of beasthood, a complete overhaul of the beasthood system, or else a new effect of the Beast Claw weapon specifically. The player character is seen using two unidentified attacks: a roar that knocks the gargoyle enemy over (gargoyles will do this normally if you hit them anyways), followed by diving on top of it and seems to bite the enemy before the scene ends (which is normally not possible, and would be very odd if it only applied to gargoyles and their unique "knocked over" animation). Unsure whether beast mode modifies the equipped weapon's moveset in some way, or else gives new context-sensitive attacks, or anything really.
New covenants/oaths confirmed so far:
- The League - soon to be the one-and-only co-op covenant for Bloodborne. The League is lead by a mysterious man in a fancy constable's attire with a bucket helmet, and players can join with his Oath and assist other players online to compete in The League's online ranking roster. League members can also summon NPCs to assist them.
New areas confirmed so far:
- Hunter's Nightmare - this was the area playable in the demo. It looks to be an area similar to the Nightmare Frontier, but with rivers of blood.
- Research Hall - location named in the official website. No further information available.
- Fishing Hamlet - location named in the official website. No further information available.
- Astral Clock Tower - location named in the official website. We have exactly one picture related to this, and no idea what kind of enemies or treasure may be found within.
New enemies confirmed so far:
- "nightmare hunters" - real name unknown, and largely irrelevant. These are typical enemy hunters, but with one notable difference: they will attack beast enemies when not attacking you. They can be distinguished from normal enemy hunters by their glowing red eyes and larger builds. The nightmare hunters seen in the demo were wielding the new DLC weapons, and in cases where they were using weapons the players had access to, the movesets were identical.
- "Cthulhu guards" - imagine the heavily armored axe wielders from Hemwick Crossing, but ten feet tall and with a tentacle grab that comes out from under their hood. Has arcane abilities they cast with their axes. Not an enemy to be trifled with.
- spoiled for boss spoilers
Ludwig - boss title is in Japanese, but early translations claim it says something along the lines of "cursed beast Ludwig" or "horrid beast Ludwig". When you first enter the arena, something that appears to be a walking corpse warns you to run away because the beast Ludwig is nearby, after which the camera shows Ludwig in the typical bits and pieces to full reveal method and the fight begins. The linked article up top mentions that his moveset was neutered for the demo fight, but he still shot jets of arcane fire every now and then.