Sachiel comes flying into an alcove formed by the buildings and crashes into one of them.
Reichu: "I always knew my soft, round Angel tush would come in handy!" Watch the building closely here — its placement shifts slightly when Sachi falls against it.
We can see a cross section of Sachiel's right arm here, which not only indicates that he has purplish "meat" (a neat touch, IMO), he also does have two bones in his lower arm after all, homologous to our radius and ulna. As I pointed out back in episode Episode #01, the ulna would be the one employed in his lance of light attack.
