Being the hoarder than I am, I’ve had this old helm taking up space in my pack for some time. Eventually, I dumped it in my bank to deal with later. Well, later is now.
Custom to place the arms and armor on a fallen warrior’s cairn. Grandfather fell not far from here. Managed to retrieve his body, but I saw an ogre with his helm.
There is a drop off an Ogre in Morkul Descent, an underground orc complex home to a legendary forge. Once you loot it, it will appear in the miscellaneous section of your inventory and have the following description
An old helm with a maker's mark from Morkul Stronghold. It's too battered to wear, and the name etched within is too faded to read.
The grandson is located at the location below. Talk to him. He will place the helm on the cairn and leave. Easiest way there is to quick travel to the Morkul Plain Wayshrine and head Northeast.