Divine Flaming Slash

This spell can only be casted when unarmed or when the caster does not hold a shield and holds a one-handed weapon.

A blast of flames sweeps out of your hands (if unarmed) or one-handed weapons (if armed with one-handed weapons). The target enemy creature must make a Strength saving throw. On a failed save, the target creature takes 1d10 + Strength modifier fire damage and becomes frightened of you for one turn. Furthermore, each ally and enemy creature within 10ft from the caster must make a Dexterity saving throw. On a failed save, nearby ally creatures within 10ft take 1d4 fire damage, nearby enemy creatures within 10ft and ally creatures within 5ft take 1d6 fire damage, nearby enemy creatures within 5ft take 1d6 + Strength modifier fire damage.

If this spell is casted while holding a weapon with the Versatile and/or Reach properties, the spell is transferred to the weapon and this adds the weapon damage to the spell damage (e.g. spell damage = 1d10 + Strength modifier, weapon damage = 1d8. Total damage = 1d10 + Strength modifier + 1d8). 

If this spell is casted after casting "The One" spell, the enemy target takes, on a failed safe, a fire damage equal to 3d20 + Constitution modifier, and another random enemy creature within 15ft receives a fire damage of 1d10 + Strength modifier.

On a successful save, the target takes half the damage and is not frightened. Furthermore, on a successful save, nearby ally creatures take no damage and nearby enemy creatures take half the damage.