Refinements:

R1: Day King's Splendor Solis

CRIT DMG from Elemental Bursts is increased by 16%. When an Elemental Burst hits an opponent, gain the Blade of the Daylight Hours effect: ATK is increased by 20%. Nearby active party members other than the equipping character have their ATK increased by 16% for 3s.
Additionally, when the party possesses Hexerei: Secret Rite effects, the effects of Blade of the Daylight Hours are increased by an additional 75%. This effect can be triggered even if the equipping character is off-field.

R2: Day King's Splendor Solis

CRIT DMG from Elemental Bursts is increased by 20%. When an Elemental Burst hits an opponent, gain the Blade of the Daylight Hours effect: ATK is increased by 25%. Nearby active party members other than the equipping character have their ATK increased by 20% for 3s.
Additionally, when the party possesses Hexerei: Secret Rite effects, the effects of Blade of the Daylight Hours are increased by an additional 75%. This effect can be triggered even if the equipping character is off-field.

R3: Day King's Splendor Solis

CRIT DMG from Elemental Bursts is increased by 24%. When an Elemental Burst hits an opponent, gain the Blade of the Daylight Hours effect: ATK is increased by 30%. Nearby active party members other than the equipping character have their ATK increased by 24% for 3s.
Additionally, when the party possesses Hexerei: Secret Rite effects, the effects of Blade of the Daylight Hours are increased by an additional 75%. This effect can be triggered even if the equipping character is off-field.

R4: Day King's Splendor Solis

CRIT DMG from Elemental Bursts is increased by 28%. When an Elemental Burst hits an opponent, gain the Blade of the Daylight Hours effect: ATK is increased by 35%. Nearby active party members other than the equipping character have their ATK increased by 28% for 3s.
Additionally, when the party possesses Hexerei: Secret Rite effects, the effects of Blade of the Daylight Hours are increased by an additional 75%. This effect can be triggered even if the equipping character is off-field.

R5: Day King's Splendor Solis

CRIT DMG from Elemental Bursts is increased by 32%. When an Elemental Burst hits an opponent, gain the Blade of the Daylight Hours effect: ATK is increased by 40%. Nearby active party members other than the equipping character have their ATK increased by 32% for 3s.
Additionally, when the party possesses Hexerei: Secret Rite effects, the effects of Blade of the Daylight Hours are increased by an additional 75%. This effect can be triggered even if the equipping character is off-field.

Your support is more valuable than a primogem.