Having looked at an awful lot of German and Swiss manuscripts in recent months, the handwriting is consistent with the first half of the 15th century (I lean 1400–1430 or so). Late 14th-century German manuscripts tend to have a double-story "a," not the single-story "a" observed here, while later 15th-century German manuscripts don't loop their "b" and "l" letters as consistently as this manuscript does.
To give you a rough sense of what I mean, here's a manuscript written in Freiburg in 1413–1415. You are not allowed to view links. Register or Login to view.
And here's a German psalter written in 1421. You are not allowed to view links. Register or Login to view.
To give you a rough sense of what I mean, here's a manuscript written in Freiburg in 1413–1415. You are not allowed to view links. Register or Login to view.
And here's a German psalter written in 1421. You are not allowed to view links. Register or Login to view.