I think this is a minor requets because the majority users won't use custom assets.
But i give my feedback, perhaps it could become usefull.

Entity editor wish list !
- Import Obj and FBX, that are the most used
Have to convert models to an outdated format is tedious.
- Import textures and auto create DDS textures with some optionnal compression choices
Actually it's tedious to have to manually convert bitmaps to DDS with another tool while it is done automatically elsewhere
- A dynamic animations list , you can enter an animation name, you can enter start and end frames, and enter animation speed (new LUA script code will call anmations names , no more frames usage)
- For an animation we can define events names, like " attack check collision" on frame 105 for example, in Lua code we could check if the event has started
- Full model 3D view, we can rotate and zoom view as we want , it will help for collisions adjusting a lot also
- Create full materials with drag and drop textures
- Be able to select exisiting materials and assign them to the model or one of it's sub model group if the model has multiple materials , this could be done with drag and drop or some material list with some slots to assign materials
- Adjust physics properties if the object is a rigid body