In the second paragraph (Itm. ij) does thassencion mean "the ascension" ?
Yes!
Sendal: A thin rich silken material (OED).
Latten: A mixed metal of yellow colour, either identical with, or closely resembling, brass (OED).
Spangle: A small round thin piece of glittering metal (usually brass) with a hole in the centre to pass a thread through, used for the decoration of textile fabrics and other materials of various sorts (OED).