You may have accidentally created a new bone called bone09. But that is unlikely seeing how it is called bone09.
What exactly did you do while looking at the model in blender? Did you copy meshes and body parts of it into an own model of your making?
Make sure that if you did that. That you copy all attached bone names as well as the body meshes (or their groups) onto the new model mesh.
Keep in mind that you can not copy paste models (for example new torsos.) onto another models head without making adjustments to the bones which are all parents of specific mesh groups. Some models got like exp. 128 bones while others perhaps only got a 100 bones. You would need to de-parent all the meshes of it's old bone structure and parent the meshes onto their new bone groups from scratch or by selecting several parts of the meshes to the desired bone section.
Bones are actually that what makes the models move later on in any game. Like our bones inside our own bodies keep us from falling and collapsing in itself to the ground as 1 large bag of water. The very fabric of what we namely are - bags of water.
I suggest you checkout some tutorials.
Check out the great tutorials made by Tetzu0:
https://www.youtube.com/watch?v=9W4RW2mA6os How to install Blender for Hl1 Gold Source Engine
https://www.youtube.com/watch?v=MbT4ShF3EQI Part2
https://www.youtube.com/watch?v=f6-6OPvrPb0 Bone tutorial on simple can.
https://www.youtube.com/watch?v=AUIFyXqYE2w Animating things
https://www.youtube.com/watch?v=StfsWz9Svms Fixing broken Animations
https://www.youtube.com/watch?v=PBLnzWSp8ug IK Bone rigging (Important regarding your current situation)
https://www.youtube.com/watch?v=ZWf1OGSaGXg Animation Tutorial2
Have fun.