The first round of Angels were designed back in 2005. Even among them, Sahaqiel is one of the oldest. I think of it as sitting close to the heart of Angelarium. An essential piece of the 15 years of art that's come since its creation.
Going back to these very old designs is a lot of fun, but in Sahaqiel's case I didn't want to mess with too much. The trick is going to be introducing enough that's fresh and new to this Angel, while still being true to the original intent.