Some random thoughts...
Holy Mistletoe: Level 4
Reagent 40 gp
Power (Consumable * Radiant): Free Action. Expend this reagent when you use a power with the radiant keyword of up to 4th level. Add 2 to any damage rolls and target is pushed back 1 square (if the power already does a push, increase pushed distance by 1 square).
Holy Oil: Level 5
Potion 50 gp
Power (Consumable * Radiant): Minor Action. Apply this potion to a melee weapon. Until the end of your next turn, the weapon does radiant damage.
HolyHand Grenade <insert more suitable name>: Level 10+
Potion
Level 10 - 200 gp
Level 20 - 5000 gp
Level 30 - 125000 gp
Power (Consumable * Radiant): Standard Action. Make a ranged attack vs reflex with a +2 bonus (range 5). Target takes 2d6+Dexterity radiant damage. If the target has radiant vulnerability, target is also dazed until the end of your next turn.
Level 20 - +4 bonus, 3d6+Dexterity Damage
Level 30 - +6 bonus, 4d6+Dexterity Damage
Holy Mistletoe: Level 4
Reagent 40 gp
Power (Consumable * Radiant): Free Action. Expend this reagent when you use a power with the radiant keyword of up to 4th level. Add 2 to any damage rolls and target is pushed back 1 square (if the power already does a push, increase pushed distance by 1 square).
Holy Oil: Level 5
Potion 50 gp
Power (Consumable * Radiant): Minor Action. Apply this potion to a melee weapon. Until the end of your next turn, the weapon does radiant damage.
Holy
Potion
Level 10 - 200 gp
Level 20 - 5000 gp
Level 30 - 125000 gp
Power (Consumable * Radiant): Standard Action. Make a ranged attack vs reflex with a +2 bonus (range 5). Target takes 2d6+Dexterity radiant damage. If the target has radiant vulnerability, target is also dazed until the end of your next turn.
Level 20 - +4 bonus, 3d6+Dexterity Damage
Level 30 - +6 bonus, 4d6+Dexterity Damage