So many

1. Toral put up no resistance and received many rough blows, so many that his face became a welter of blood and wounds.

2. Swein sidestepped it easily, and they traded more blows, so many that Athelstan's arms grew weary as he parried and dodged

Q1) I'm curious whether in both sentences "so many" is used correctly used and how to grammatically analyze "so many".

Q2) Is "so many" used as an adverb or adjective? and what is it grammatically modifying in them?