What happens when a Shadow Blade on which Darkness has been cast disappears?

Question

The darkness spells states the following:

If the point the darkness spreads from is an object you're holding or one that isn't being worn or carried, the darkness comes from and moves with the object.

However, there is no prescription for what happens if the object that the darkness is following is broken (What happens to the darkness spell if it is cast on an object that then breaks?) or destroyed, such as when shadow blade disappears after being let go of by the wielder/caster. What would happen to the darkness spell and its positioning? What would happen if the same object were to reappear in space, as is in this case suggested by the phrasing of the shadow blade spell (emphasis mine):

While the spell lasts, you can use a bonus action to make the sword reappear in your hand.

To me, the most reasonable outcome in the event of the object outright being removed from existence is that the darkness stops being emitted, as the darkness is stated to 'come from' the object. The darkness would then reappear should the same object reappear, provided that the spell hasn't ended (no trigger for which has been activated).

Answer 1

I see three different cases here:

1. The object no longer exists: There is good authority that if the target of a spell or effect ceases to be a valid target (e.g. by no longer existing) then the spell or effect ends. So, the darkness ends.

2. The object is broken into several different objects: Well, those objects weren't the target of the spell so the darkness ends.

3. The object is elsewhere: If the same object can be recovered from the elsewhere then it is still the valid target so the spell continues.

As a side note, it is not clear to me that Shadow Blade actually creates an object that would serve as a valid target for the Darkness - I could entertain arguments either way about this.

Answer 2

You are correct; the darkness would disappear when the object disappears, but when it comes back, the darkness would come back.

the darkness emanates from the object

So if the darkness cannot emanate from the sword, there is no darkness while it has disappeared.

I would assume that the darkness spell would continue to exist if the object disappeared, as the darkness comes from the sword, and the sword still exists, unlike the question you referenced. There is no ending condition for the darkness spell, other than it overlapping with a higher-level spell that gives off light and the concentration from being broken. The object still exists, so when it comes back, it will give off darkness.

Answer 3

You cannot cast darkness on a shadow blade because they both require concentration.

You can ask another player to do this, but the other player must be holding the sword to cast the darkness, as the darkness spell says "an object you are holding or one that isn't being worn or carried,".

However, another person cannot cast darkness on your shadow blade if he is not holding it, and you cannot hand it over to your friend because the shadow blade spell says "If you drop the weapon or throw it, it dissipates at the end of the turn".