SkinnedMesh humanoid character animated but has no Transforms rig?...

I've imported a humanoid model by 3DMaesen (was on the asset store but now deprecated, although you can still get a version from Sketchfab)
It has animations (a clip in the fbx which animates the model when placed in an animation controller) but not rig - just skinned meshes (no hierarchy of transforms, like I'm used to seeing)

Can anyone explain what's going on, and how I would do something like add a sword - which I'd usually place in the hand transform?

Thanks !

ps. for bonus points... I'd also love to know if the Warning (see screenshot) is something I can fix and/or should worry about. Ideally I'd like to use other humanoid animations with this model. Will the rotation offset cause a problem?

 

What does the heirarchy look like when you drag it into a scene? I'd assume that since you can import it as a humanoid rig it has a rig in there somewhere.

 

@leftshoe18 So I've now double checked, and I'm not going mad... no, the hierarchy view is like the fbx, no rig. But it is animating...
https://www.screencast.com/t/gmMlHXSH

 

Ah! Got it... The rig is set to 'Optimize Game Objects ticked on...

from the docs: https://docs.unity3d.com/Manual/FBXImporter-Rig.html

Optimize Game Object Remove and store the GameObject transform hierarchy of the imported character in the Avatar and Animator component. If enabled, the SkinnedMeshRenderers of the character use the Unity animation system’s internal skeleton, which improves the performance of the animated characters.

Only available if the Avatar Definition is set to Create From This Model.

Enable this option for the final product. ​