Related to my other question about illusions and true sight, the third comment on this answer here brings up a question on how true sight interacts with illusory reality.
Illusory Reality: At 14th level, you can weave shadow magic into your
illusions. When you cast an illusion spell (that isn't a cantrip), you
can choose one inanimate, nonmagical object that is part of that
illusion, and declare it to be real, as a bonus action on your turn.
The object can't deal damage or harm anyone, and it remains real for 1
minute.True Sight: This spell gives the willing creature you touch the
ability to see things as they actually are. For the Duration, the
creature has truesight, notices secret doors hidden by magic, and can
see into the Ethereal Plane, all out to a range of 120 feet.
I'm assuming since the object is now real, true sight would just see the object? At least for the duration of illusory reality?
Best Answer
The object is as real as it gets. It would be the same as creating any other object that can be seen and touched. The idea is to add some tangibility to your illusions via an additional aspect of magic (shadow magic). True Sight would reveal the illusion as false, but the object actually exists in space and so the creature sees that as normal. Whatever information the creature knows about the object is up to circumstances and your DM.
For instance, if the creature walked into an illusory house you made and you also made a chest real inside of it, there's no real way for it to know the chest isn't permanent (isn't real) unless he inspects it, or saw you create it, or otherwise reasoned its genuineness.
The fact that the object can deal no damage may or may not affect the way your DM rules the reality of the object. Surely a dagger made real should deal damage, and yet it cannot. My out-of-game reasoning for this is more about balance. I don't think the rule makers want you to use 1st-level spell slots to create grenades and daggers and other harmful things. In-game, i might suspect the material is weak or the object governed by special shadow magic rules. Your DM can handle the in-universe reasons for why a real object wouldn't be able to damage anyone.
So how do you handle a real weapon that can't deal damage with true sight? I think there are a number of explanations you could have for why a real dagger wouldn't deal damage, but at the end of the day, all that matters is that True Sight sees the object as real, because it's not an illusion. See is the key word here, since true sight has nothing to do with inspection, touch, or investigation. True Sight is set apart from intelligence. Think of it like a plastic bowl of fruit. It's real, right? But, until you actually inspect the fruit, you don't recognize it as a fake real item. Real being opposed to illusory here, not opposed to genuineness.