1. The Weapon
The "Ashina Arsenal" weapon uses the same scaling formula as the "River of Blood". That means, all damage types will scale with Arcane. I also disabled the critical hit (like those whips) and jump/fall attacks in consistent with Sword Saint's fighting style. 

2. Other items
There are 3 talismans (Mushin Esoteric Text, Ashina Esoteric Text, Tomoe Esoteric Text) unlock extra lives and phase specific skills. Full set of Ashina Armor pieces provide the top protection (maximum by entry across all pieces of the same type). Ashina Greaves also provide immune to fall damage and instant death. The heavy Ashina (body) Armor actives "Bull-Goat Tallisman" effect. 

3. Getting items
All mod items can be obtained as "Ashina Elite" (added new class after Wretch). In mid game, players can find the weapon, talimans and armor pieces in crafting menu. Weapon can be crafted for free, but the other items require boss remembrance to offer some progress scaling (Mushin Esoteric Text - Godrick, Ashina Esoteric Text - Rennala, Tomoe Esoteric Text - Lichdragon, Gauntlet - Radahn, Greaves - Rykard, Helmet - Regal Ancestor, Armor light - Morgott, Armor heavy - fire giant). 

4. Damage types
Although the weapon has all damage types in the info page, only one type of damage is active for each attack. Standard attacks, including the blade-reach sub-attacks for skills, are purely physical. Shura (修罗phase 2 1-hand katana with Mushin Esoteric Text) flame attacks obviously invoke fire damage. Dragon flash attacks (white blade beams or sweep) are magical. The open gate sweep is holy damage. The Tomoe lightnings are obviously lightning damage. 

5. Attack effects
Posture damage is reserved to mimic "lightning shock (打雷)" of the Tomoe moves. The Hemorrhage effect shown in description is reserved to mimic "burning (爽上)" of the flame attacks. Both posture damage and Hemorrhage are completely removed elsewhere. 

6. Damage level and super armor
To compensate for long charge before most attacks, toughness before hit is greatly enhanced, and the damage levels are raised to the level of great/colossal swords (e.g. single hit katana staggers armored knights). For selected moves that cannot be interrupt in Sekiro boss fights, players will have a super "endure" with 80% damage reduction (like Ashina Cross, Dragon Flash). 

7. Defense
"Ashina Arsenal" in right hand completely ignores the left hand weapon. L1 will always be guarding with right hand katana. During the 0.7 second raising guard animation (perfect block), the play has perfect defense. Guard poke (L1+R1) will perform parry. Guard R2 will always perform the guard counter with or without being hit. 

8. Phases
Player activates the phases I-III by taking the appropriate style, resurrecting specific times and equipping the required talisman (Esoteric Text). "Ashina Esoteric Text" must be equipped for unlocking and maintaining 2H style. 
Phase I: a) active after reload/teleport/respawn/grace rest without dying; b) must take 1 hand style; 3) no esoteric text required but "Ashina Esoteric Text" unlocks 1 hand dragon flash and open gate. 
Phase II: a) active after dying at Phase I in 1 hand style with "Ashina Esoteric Text" or "Mushin Esoteric Text"; b) must take 2 hand style with "Ashina Esoteric Text" (Sword Saint 剑圣 phase 2) or 1 hand style with "Mushin Esoteric Text" (Shura 修罗 phase 2); c) the 1 hand Shura (修罗) phase 2 overwrites the ichimonji R2 and adds a few more flame attacks; d) the 2 hand Sword Saint (剑圣) phase 2 unlocks 2 hand dragon flash attacks (while you can fight in 2 hand style at phase 1 with "Ashina Esoteric Text" but no dragon flash attack or resurrection). 
Phase III: a) active after dying at Phase II in 2 hand style with "Ashina Esoteric Text" and "Tomoe Esoteric Text"; b) two powerful lightning attacks instantly stance break enemies ignorant of "lightning reverse" (if they somehow evade the attack and hit player, player will be faceplanted regardless of the damage level). 
The gesture "Extreme Repentance" has been overhauled by a suicidal seppuku to enable instant death for phase progression (added to starting gestures for "Ashina Elite"). 

9. Skills and FP costs (optional file 1)
All skill FP cost is consumed at the first animation of combos. Follow-ups are FP free. 
Phase 1: Push Thrust 0, Dragon Flash Beam 25, Dragon Flash Sweep 25, Open Gate Sweep 40
Phase 2: Shura Catch 10, Shura Ichimonji + Flame Slash 25, Shura Stomp + Fire Wall 25, Shura Stomp + Flame Sweep 25, Shura One Mind combo (O Burn Flame + One Mind Blade Storm) 40; Sword Saint Dragon Flash Sweep 25, Sword Saint Dragon Flash Beam 25, Sword Saint Sakura Dance Dragon Flash 25. 
Phase 3: Tomoe Back Jump Lightning 40, Tomoe Forward Jump Lightning 40. 

10. Sound modding (optional file 2)
Reload/respawn/teleport/grace: 迷えば, 敗れる (Hesitation is defeat). 
Phase progression start: Isshin's groan at phase progression. 
Phase 2 start: 参れ (Go forward), Godfrey Phase 1 BGM. 
Phase 3 start: まだじゃ (I'm not done),  Godfrey Phase 2 BGM. 
Switch to 2 Hand: 血が, 滾って来たわ! 行くぞ (My blood boils. Go!).  
Death: 見事じゃ (Beautiful work). 
To stop BGM: 1) rest at grace; 2) perform "finger snap" gesture (learned from Kale to call Blaidd). 
Gesture "Rallying Cry": added Sengoku style "hei" "hei" "Ho!!!!".