My campaign set in the Faerûn's Sword Coast consists of 5x level 7 PCs:
- a goliath barbarian armed with his tribe's ancient naginata
- a human paladin armed with a holy avenger
- a tiefling samurai armed with Zariel's cursed sword
- JaonsJason: an eladrin champion armed with a hideously overpowered Moonblade
- a soulless human eldritch knight with nothing.
Let me tell you how they got here.
The campaign has seen Jason, due to a magical disease, accidentally (through a random roll on a chart of my own design) transform from a human into an eladrin therefore enabling him to attune to the Moonblade that's subsequently become, in his inhuman hands, a Moonblade that's a +4 longsword.
Later, after defeating an adult red dragon, in addition to boots of haste, a lot of gold, and the holy avenger the paladin now wields, the party discovered a deck of many things. Before I could tell the eldritch knight's player what I'd planted in the dragon's horde for his PC, the eldritch knight drew from the deck, pulled the void, and saw his soul imprisoned.
At one point, thieves tried to take some of the PCs' stuff—they nicked the PCs' bag of holding—, but the PCs tracked the thieves back to their lair and intimidated the thieves into giving the PCs back the stolen goods.
So, now, the party is extremely unbalanced. Specifically, the other players feel that their PCs are overshadowed by Jason the Moonblade-wielding eladrin who deals over 120 points of damage per turn.
I'm considering having an NPC associated with the Moonblade demand it be returned to its rightful owner—that is, the NPC himself—, but I'm not sure how that will go over. And that doesn't solve the problem with most of the other PCs still having incredibly powerful weapons.
How can I keep the the players happy yet take away Jason's Moonblade and the other PCs' overpowered magical weapons and simultaneously reward appropriately the eldritch knight?