If you want such a symbol to appear in game you have 3 options...
- Give the unit an item with the model as an attachment on the appropriate attachment point (head).
- Give the unit an aura with a buff of the model as an attachment on the appropriate attachment point (head).
- Use triggers to create a special effect attached to the unit of the model as an attachment on the appropriate attachment point (head). This special effect can be saved to a variable for deletion at a later time.
You could also edit the model to add the desired geometry and animations to it. However this is generally not recommended over any of the above.