Melee weapon with projectile style ammo system.

Is there any way for melee items to use the same drag and drop ammo system as bows and the like.
Essentially I want to be able to drop an item onto the spear that changes it to a different spear, the player hits something and the other spear does its thing and changes back into the base spear.

Base spear + greanade = explosive spear
-the player strikes a wall, explosion, and the explosive spear reverts with a ton degradation.

Right now is this possible? Not realistically in the least. The amount of blueprinting that would need to be done to get this working, would make it not worth the time right now, and that is provided that all the variables you would need for this would be exposed.

Once the Total Compatibility Dev Kit update comes out, then theoretically yes, it should be do-able.

Well an easy way to have a spear revert is to keep the pickup as a regular spear if you happen to be throwing it; otherwise what you could do is have your explosive spear with very low durability but just before it is destroyed it drops the original version of the spear. Getting the spear to transform in the player’s hands may be particularly difficult to accomplish but I don’t doubt it is possible for UE4. To me it just really seems to depend on how you want to approach it.