Stood by them (epestē autois). Ingressive aorist active indicative. Stepped by their side. The same word in Act 12:7 of the angel there. Paul uses it in the sense of standing by in Act 22:20. It is a common old Greek word, ephistēmi.
Were sore afraid (ephobēthēsan phobon megan). First aorist passive indicative with cognate accusative (the passive sense gone), they feared a great fear.