Charles - That is a very nice letter from Eberhard Heder, who I have had the pleasure of meeting with in person several times. He is a real gentleman.
Unfortunately, information from Wolfgang Vopersal is not always accurate despite what I am sure was his best efforts. (just like some of my own information) One of the key information sources for my Führerliste publication entries for "Wiking" Pionier officers was the excellent Pioniereinheiten der 5.SS-Panzer Division „Wiking“, privately published by Kurt Imhof in the 1980s. Ostuf. Julius Weck is not listed there as a battalion commander nor is he listed in my Führerliste as a battalion commander. On page 230 of Imhof's publication Weck is listed as wounded in February 1945 as commander of the 3rd Company.