For the first day of Wagram, which seems to be the time of the order of battle for Brigade Weiss that you are doing, we have the following for Landwehr in Brigade Weiß (there were re-assignments before and after this day).
Usually the Austrian order of battle for Wagram shows this Landwehr batallion associated witth IR3 Erzherzog Karl
Viertel Ober dem Manhartsberg Landwehr
2. Battalion Waidhofen an der Thaya ("2. OMB") : Major Anton v. Eisenkolb, später Major Baron Clemens v. Beissel, später Major Graf Franz v. Schönborn
However in the regimental history of IR3 and some other sources, the battalion is given as this one (note that the Major Graf v. Schönborn also commanded this battalion):
Viertel Unter dem Manhartsberg Landwehr
2. Battalion Ernstbrunn ("2. UMB") : Major Graf Joseph Heinrich Obergfell, später Major Graf Franz v. Schönborn, später vacant (Oberstleutnant Graf Johann Heinrich v. Hardegg)
In either case these were "Lower Austria" Landwehr and uniformed accordingly. From the Bilderseries of Hause Joseph Eder (Wien, 1810):
The other Landwehr battalion in Brigade Weiß, the one associate with IR 50 Stain, is usually given as the following (note that we have the Major Baron v. Beissel changing commands):
Viertel Unter dem Wiener Wald Landwehr
4. Battalion Wiener Neustadt ("4. UWW") : Major v. Buol, später Major Baron Clemens v. Beissel
Between the rather constant brigade re-organizations, the changing battalion commanders, the use of geographical indentifications differing only in "Ober" vs. "Unter", and the use commanders' names for identifying battalions, to be quite sure of the Ausrrian order of battle is really rather a substantial challenge. Likely the only way to be sure is to get the formations' officer lists and check the indiviual service records (if they exist) for a sample the units' junior officers.
While I can often do that for French and Russian junior officers, I am not knowledable enough of the careers of Austrian officers. Perhaps another colleague can help.
- Sasha