The Queen's Domain Holy Sword upgrades follow a three-step path that no other weapon has. Endu becomes Soul Bound Endu, Soul Bound Endu becomes True Holy Sword Akunra, and each step extends how far you can fly. The third step is not just a level-up — it needs five Wind Gems, the Storm Gem, and a trip to an altar at the bottom of the Deimpo Mausoleum.
Queen's Domain Holy Sword upgrades: the three-step path
- Take the Endu to weapon level 10. It becomes the Soul Bound Endu.
- Take the Soul Bound Endu to weapon level 10. It becomes the True Holy Sword Akunra.
- With the True Holy Sword in hand, reach the Altar of Purification in the lowest layer of the Deimpo Mausoleum to finish the path.
The altar is the awkward part of this list, and the route into that lowest layer is in the Deimpo Mausoleum guide. The door to the altar is not inside the mausoleum itself — it is in Verdant Woods, and it opens once you dispel the eight green sigils there with the Mask of Second Sight and Sipeha's Lens.
What each upgrade gives you
Every step makes the sword travel further, and the flight distance is the actual point of the upgrade — the Endu is a traversal item first.
- Endu flies you between platforms and opens ledges and islands that cannot be reached any other way.
- Soul Bound Endu extends that range further.
- True Holy Sword Akunra extends it again, and at full upgrade the sword lets you dash ten times.
That ten-dash figure is not cosmetic. The Ancient World pyramids and the Petrified Garden both assume you have that many air dashes available, and the endgame areas are tuned around it. The movement techniques that use it are in the movement tech guide.
The last step needs more than the sword
The final upgrade is gated on collection, not on a level.
- All five Wind Gems collected. They are the gating currency of the late game — one Ancient World pyramid needs the full five air dashes unless you use the Cestus plus three, and the Petrified Garden and the giant bell at the top of the Tower of Knowledge assume all five. Where each gem is is in the Wind Gem guide.
- The Storm Gem recovered. It is a separate unlock in the Tower of Knowledge, and it is what adds the Special Attack meter. Where it is and how to fire it is in the Storm Gem guide.
The Storm Gem also opens the special attack on its own, independent of the sword upgrade, so it is worth picking up even if you never finish the Endu path.
The Storm Gem unlocks the special attack meter
Once you have the Storm Gem, press R on keyboard, or Triangle or Y on a controller, to fire the gem's special attack, and you do not need to be holding a sword to use it.
The meter starts empty and is charged by defeating enemies first, so the gem pays off only in fights where you have just killed something — it gathers energy the same way magic weapons do. That is the one thing to keep in mind about it: it rewards aggressive fights rather than patient ones.