I've finally unearthed some information on the former soldier you fought. The trail was difficult to follow, as this particular family tree was not properly documented, but I've found a blood relative at last.
Would you believe Caretaker Alen at Light's Hope Chapel is, in fact, Christoph's son? It might ease his mind to hear of his father. If ever you find yourself in service to the Argent Dawn within the Plaguelands once more, please, speak with him. It would be a kindness.