Auftraggeber

1. principal
2. employer
3. client, customer

des

genitive masculine/neuter singular of der: the

Schreins

genitive singular of Schrein

war

1. first-person singular preterite of sein
2. third-person singular preterite of sein

Erzbischofs

genitive singular of Erzbischof

Gregor

a male given name, equivalent to English Gregory

von

1. from
2. of, belonging to (often replacing genitive; see usage note below)
3. by (with passive voice)
4. about, of (a topic)
5. on, with (a resource)