Why do I torture myself?

NOTE: This was played on PC with the Completionist Save Files. The "Endurance Challenge" was made by me for me but you can apply your own rules. Even though I have max BP, Nanopastes were picked up during final phase for the S rank.

TIMESTAMPS:
00:05 - PHASE 1
01:40 - PHASE 2
05:23 - FINAL PHASE

General Boss Rules:
Revengeance Difficulty.
Full Health Upgrades and Full FC Upgrades.
Fully Upgraded HF Blade and Fully Upgraded Murasama.
No Nanopastes and/or Electrolytes.
No Special Weapons.
No Special Armor (Default and Reskins only).
No Sub-Weapons/Equipment.
No Wigs.
No Ripper Mode.
No Skills used except "Offensive Defensive".
No Autosaves/Restarts.
No Hit/Damage.
Has to be an S Rank. (It doesnt show for some reason at the end, and this only happens for Armstrong :/).

PHASE 1:
Armstrong HAS to taunt ONCE.
Survive until music ends.
Be close to him as much as possible.

PHASE 2:
Armstrong HAS to taunt THREE TIMES.
You HAVE to fight him face to face. (Dodging grabs and nano blasts (yellow attacks) here and there is allowed).
Survive until his special animation plays out.
Do scripted death QTE.

FINAL PHASE:
No Heavy Attacks.
QTEs are mandatory.
No Excelsus Boulder Throw cheesing (HAVE to slash all Excelsus Parts).
Armstrong HAS to complete at least one healing cycle (above 100% HP).
Armstrong HAS to complete at least one healing cycle again (above 50% HP).
Slash through Last Excelsus Boulder Throw (5 slashes needed instead of the usual 3, not counting Armstrong's head).
Don't. Fuck. Up. Last. QTE.