Runeforged Weapons

Inevitably, the PCs are going to want to craft runeforged weapons for themselves in order to take on Karzoug. I want to talk a little about how I see these being implemented in a 4th edition game. There are a number of considerations to take into account here - Should the runeforged enchantment replace the weapon's enchantment, or simply augment it? How should the traits manifest (the actual mechanics of the enchantment)? Should PCs be allowed to enchant implements in addition to weapons? Should an associated increase in value be added (in case, for instance, the party wanted to sell or disenchant the item)? Should the Transfer Enchantment ritual affect the runeforged enchantment, and if so, how? Let's break it down.

In the original adventure, as part of the 3.5 mechanics, the runeforged weapons were simply additional enchantments that a weapon could gain (they had a +2 bonus attached, and increased the value of the weapon accordingly). The goal here should be to provide the PCs with a weapon they will actually want to wield. To that end, having the new enchantment replace the old would be counter-productive; it would not be unlikely for a PC to decide that the current enchantment on his weapon is a better fit for him than whatever enchantment a runeforged weapon might provide. On the other hand, simply providing an additional effect will make the PCs slightly more powerful than is expected of them at this level. This is a balance consideration, then. One thought I had was to remove a couple treasure parcels from the allotment in order to offset this new source of magic item power.

In order to avoid penalizing implement-wielding characters for no particular reason, runeforged enchantments should apply just as easily to implements as they do to weapons.

Regarding the actual properties of the runeforged weapon enchantments, each should definitely be unique. While some mechanics are easy to translate over to 4th edition, others are less straightforward. Covetous weapons, for instance, are easy to adjudicate - fire resistance and the fire subtype both exist in 4th edition. The Tyrannical enchantment, on the other hand, runs into issues; PCs do not usually fight monsters that are "summoned" in the same sense that PCs can use powers with the summoning keyword, and an effect equivalent to dismissal is clearly too strong an effect to attach to the weapon. Additionally, the spellcaster-damaging property on each weapon is a problem, as school distinctions no longer exist. Here are my thoughts on each enchantment, for right now:

Miserly Weapon/Implement
Property: Whenever you make an attack using this weapon or implement, you gain an item bonus to the attack's damage rolls against shadow creatures equal to the weapon's (or implement's) enhancement bonus.
Power (Daily): As a minor action, you touch your weapon or implement to any adjacent illusion you have seen through with a successful Insight check. Effect: All allies within 10 squares can also see through the illusion as though they had made a successful Insight check.

Covetous Weapon/Implement
Property: Whenever you make an attack using this weapon or implement, you gain an item bonus to the attack's damage rolls against creatures with the fire keyword equal to the weapon's (or implement's) enhancement bonus.
Property: You gain resist 5 fire.

Jealous Weapon/Implement
Property: Whenever you make an attack using this weapon or implement, you gain an item bonus to the attack's damage rolls against undead creatures equal to the weapon's (or implement's) enhancement bonus.
Power (Daily): Free Action. Trigger: You would take necrotic damage from an attack. Effect: You ignore all damage from the triggering attack.

Domineering Weapon/Implement
Property: Whenever you make an attack using this weapon or implement, you gain an item bonus to the attack's damage rolls against creatures with the shapechanger keyword equal to the weapon's (or implement's) enhancement bonus.
Power (Daily): Free Action. Select a penalty from a single source that you are currently suffering from. Until the end of the encounter or until that penalty would expire (whichever comes first), you are no longer suffering from that penalty.

Tyrannical Weapon/Implement
Property: Whenever you hit a minion with an attack using this weapon or implement, you gain temporary hit points equal to the weapon's (or implement's) enhancement bonus.
Power (Daily): Free Action. Trigger: You hit an immortal creature with an attack using this weapon or implement. Effect: The immortal creature is dismissed (save ends). While dismissed, the target cannot take actions and cannot be targeted. On a save, it returns to the space it was last in. If that space is occupied, the target returns to the nearest unoccupied space of its choice.

Sadistic Weapon/Implement
Property: Whenever you make an attack using this weapon or implement, you gain an item bonus to the attack's damage rolls against creatures marking you equal to the weapon's (or implement's) enhancement bonus. 
Power (Daily): Immediate Interrupt. Trigger: An enemy within 10 squares succeeds on a saving throw against an effect caused by you. Effect: The triggering enemy fails the saving throw instead.

Parasitic Weapon/Implement
Property: Whenever you make an attack using this weapon or implement, you gain an item bonus to the attack's damage rolls against any creature suffering from a charm effect equal to the weapon's (or implement's) enhancement bonus.
Power (Daily • Healing): Free Action. Trigger: You hit an enemy suffering from a charm effect with an attack using this weapon or implement. Effect: You gain hit points as though you had spent a healing surge, and one charm effect of your choice on the target ends immediately.

The question of value is one that must be addressed. If a runeforged enchantment adds potent abilities, shouldn't that be reflected in the item's value? This is especially true if we then reduce the number of magic items the party will receive in order to balance the enchantments out. My current thoughts are to simply increase the effective level of any runeforged weapon or implement by 1 for the purposes of determining its value.

Transfer Enchantment should work to the players' benefit here, allowing them the choice of transferring either all of a given weapon's (or implement's) enchantments (both magical and runeforged) to a new weapon or implement, or just the runeforged enchantment. A runeforged enchantment cannot be transferred to a non-magical weapon or implement, however.

Let me know what you think of these ideas. Given the very limited nature of these enchantments' use (only a handful can be made, and they are only intended to be used for the final adventure of a single campaign), issues of balance aren't of critical importance, but should still be kept in mind.