Perfikot didn't immediately grant Oliver a development document. Although she could write it on the spot, she hadn't officially been enfeoffed as the Northern Guardian yet, and hadn't received the relevant seals and such. Anything she wrote now would appear somewhat unofficial.
After all, this is her first loyal vassal. Perfikot still hopes it can be more formal, and she also needs to discuss with the old butler.
Of course, the most important thing is that Perfikot wishes to enfeoff her first vassal at the ceremony where she is officially enfeoffed as the Northern Guardian. This not only adds a sense of ceremony but also showcases her majesty to the world.
At the very least, she won't be seen as a commander without even one vassal under her command.
Though as long as Perfikot is willing, there'll be plenty of people eager to follow under her banner.
