Stood by them (επεστη αυτοις). Ingressive aorist active indicative. Stepped by their side. The same word in Acts 12:7 of the angel there. Paul uses it in the sense of standing by in Acts 22:20. It is a common old Greek word, εφιστημ.

Were sore afraid (εφοβηθησαν φοβον μεγαν). First aorist passive indicative with cognate accusative (the passive sense gone), they feared a great fear.