The moment depicted is when Jesus steps out of the tomb. Notice that in the Boppard panel, Jesus steps out from a grave that everyone would have recognised at the time, not a sepulcher (a small room or monument, cut in rock or built of stone, in which a dead person is laid or buried) as described in the bible. This makes the scene far more accessible to all. The visit by the two Marys, when an angel rolls back the stone from the tomb entrance comes later in the story. Jesus does not need help to leave the tomb.
Jesus gives us the standard Christian blessing with his right hand while holding a red and white banner in his left. There appears to be a whole host of reasons for these colours including red for the blood of Christ and white for purity. I can’t find any definitive statement on the manner. Please add a comment below if you know more detail on this! Notice the clear sign of the nail on Jesus’ foot to remind viewers that this is after the crusifixion.
The angels have fabulous wings that they seem to flap in pleasure whilst the two soldiers, one still asleep and the other in surprise and awe as shown in the latest armour of the time as we have seen on other panels.
The whole depiction would have been very ‘modern’ when it was first created.
A very similar depiction of the resurrection is from the French early 15th century window, “Scenes from the Life of Christ”, shown in the “Christ before Pilate” blog. As Jesus steps out from the tomb and gives us a blessing, you can just see the soldiers and others cowering behind.