Which weapon works with your style or art
A breathing style or blood art only shows its moves while you hold a weapon that carries it. Breathing needs a katana, any katana, and not the Cutlass. Stone needs the Axe and Mace. Blood Manipulation works only with Sickles, Shockwave with bare hands, Claws or the Gauntlet, and Claws carry most of the other arts.
Breathing: hold a katana
Learn Wind while holding the Cutlass from Zuko and the key row shows only the Cutlass’s own skills, with no Wind bar. Swap to the plain Regular Katana from the shop and the Wind keys and a Wind Mastery bar appear. If your breathing moves will not work, use a katana, not the Cutlass.

Just after learning Wind, Cutlass in hand: three keys over the hotbar, F Z X, and a single bar, Sword Mastery Lv 41. No Wind bar.

With the shop's Regular Katana: the row grows to F Z X C V B and a second bar appears, Wind Mastery Lv 1 0 / 30.
Any katana will do
Wind casts from a shop katana; you do not need the Wind Katana. The Sound Katanas, which have no tree of their own, reportedly work with whatever style you have. No katana card gives a bonus to one style, so a style’s own katana looks like a stat choice, not a requirement, though players disagree on whether the Nightfall Serpent Katana helps Serpent. Where each katana drops is on the weapons page.
Stone is the exception
Before launch its trainer would not teach empty hands and sent players for an Axe and Mace first, and Stone’s moves are cast with it, so get the Axe and Mace before you train. Its drop is on the Stone page.
Bare hands, the Spear, the Tanto, the Gauntlet and the Shotgun are untested with breathing styles, so stick to a katana. The style list is on the breathing styles page.
Blood Demon Arts and their weapons
A demon’s art attaches itself to a weapon that carries it. Unlock Blood Manipulation while holding War Fans and you get no art bar and no moves; pick up Sickles and the moves and a Blood Manipulation bar come straight up.
| Art | Fists | Claws | Gauntlet | Sickles | War Fans |
|---|---|---|---|---|---|
| Blood Manipulation Gyutaro's | No | No | No | Works | No |
| Shockwave Akaza's | Works | Works | Works | No | Untested |
| Cryokinesis Doma's ice | Works | Works | Works | Untested | Works |
| Pyrokenesis exploding blood | Works | Works | Works | Untested | Untested |
| Reaper the art, not the fighting style | Works | Works | Works | No | Untested |
| Arrow, Dream, Obi Manipulation, Tamari the rest | Works | Works | Works | Untested | Untested |

Sickles in hand: eight keys, F Z X C V B N K, and two bars, Blood Manipulation Mastery Lv 35 and Sickles Mastery Lv 38.

Claws in hand, casting ice: Claws Mastery Lv 57 beside Cryokinesis Mastery Lv 69, and the last two keys padlocked.
Blood Manipulation is the one art that needs Sickles. Plain Sickles from Hoyuzo work as well as Gyutai’s Blood Sickles, and the Damascus pair reportedly works too. Every other art reportedly takes Claws or the Gauntlet instead.
Shockwave is not an item in your bag: it goes on your bare hands, so use your fists. Some Shockwave and Reaper players carry Sickles as a second weapon, for the Sickles’ own skills.
Bare fists carry the rest too: Dream, Obi, Arrow, Tamari and Pyrokenesis have all been cast with the fist slot selected, and the Combat card says most demons cast their Blood Art through bare fists when no weapon is drawn. Tamari has also been seen on Claws.
The Gauntlet is sold by the Black Marketer, and demons reportedly can use it. Every weapon source is on the weapons page, and every art on the Blood Demon Arts page.

Gauntlet, Legendary: +2 (Additional Damage), 1.04x, +2.55 (Block Points). Source Sold by Black Marketer.
At launch, arts reportedly could not be used with weapons yet. That has since changed, so an answer saying fists only is out of date.
Weapon skills live in the same tree
Most weapons you own add their own branch to your skill tree; the tab lists them, for example Flame, Spear and Cutlass together. With a demon weapon and an art, the key row runs to eight: the art on Z to B and, it appears, the weapon’s own two skills on N and K.
Some weapon skills are a boss drop you then buy in the tree. The Cutlass’s second skill, Quick Draw, is a 25% line on Zuko’s bar, and you must still unlock it in the tree after it drops. Hoyuzo’s Sickles skill is struck through with Missing Sickles until you own Sickles.

One tree for everything you own: the tab reads Character, Flame, Spear, Cutlass and Rengoku, with Flame Tiger UNLOCKED.

The Sickle Reaper Hoyuzo, 1445 / 1445, Rare Chest. Under the bar: Exp +360, Wen +160, Demon Horns x3 (50%), a struck-through Scyther Vortex x1 (10%) marked Missing Sickles, and Sickles x1 (3%) marked Lvl. 52. This is the earliest build seen; later bars read 7%.
Why the last move will not drop
A style’s fifth move needs three things: mastery 53 on that style, the move’s scroll from its Hashira, and the skill points. The scroll only drops for a player who qualifies, and the line under the boss’s bar tells you which part you are missing:
Must be SlayerYou are a demon, or have no breathing yet. (Demon arts print Must be Demon.)
Missing StoneYou have not learned the style or art this scroll belongs to. The same shape names a weapon: Missing Sickles.
Unlock PreviousYou know the style but have not bought the moves before this one in the skill tree.
Already HaveYou own the move already.
Unlock Previous is the trap: farm while it shows and you can spend hours on a Hashira for a scroll that probably cannot drop. Buy moves one to four first, then farm. Even the first move is not free: after training it costs 3 skill points in the tree. How much mastery each move takes is on the mastery page, and which Hashira drops which scroll is on the bosses page.

Character, Stone and Himejima: Arcs of Justice struck through, Defeat Gyorei, Skill P.., REQUIREMENTS NOT MET, with 11 SKILL POINTS in the bank.

Rengu after the patch: Flame Haori Style 2 x1 (3%), Flame Katana x1 (5%), Flame Slayer Uniform x1 (5%) and Purgatory x1 (10%). No kill counter anywhere on the bar.
The scroll rate itself went up. Seven of the eight Hashira scroll lines went from 5% at launch to 10% after the v.09 patch, while the katana and uniform lines on the same bars did not move.
The 35-kill pity
Yes, for skill scrolls. The V0.135 change-log reads Added pity to skills unlock (35 kills). Kill the same Hashira 35 times and the scroll is guaranteed; Thunder and Insect last moves and Illusory Light have all been reported to land at 35.
No bar shows the counter, and it may not carry over between servers. The pity covers skills only, not katanas or outfits. Some scrolls have taken 50 or even 100 kills, one of them before the pity existed. Kills made while the line reads Unlock Previous probably cannot drop the scroll and may not count towards the pity, so buy the earlier moves first.
Watch the art attach to a weapon
The ONLY Demon Guide You Need In Slayers 2! (Noob to Endgame)
Blood Manipulation learned with War Fans in hand, then working once Sickles are picked up.