Stephen saw Him as did John before their deaths. What purified them? Go back to Moses who on Mt Sinai was with GOD though he could not see Him but only a shadow? Or back to the N.T. what happened to Saul going to Demascus? Did he see anyone? No. He only heard. Why? Saul had to ask who he was talking too. Stephen did not have to be told whom he was seeing before he was stoned too death. Christ purified Stephen just as Christ had purified His disciples who walked and talked with Him after His resurection.
Christ imediately after His resurection He first appeared to a few of His disciples and at that time told them not too touch him yet because He had not been before The Father. He went before the Father in a period imediately after His death and after His disciples saw him tHim the first time. During that time His Father accepted The Lamb of GOD's sacrifice. The purification for you, me, Mary, and all who believe was completed and accepted.
17“Don’t cling to me,” Jesus said, “for I haven’t yet ascended to the Father. But go find my brothers and tell them that I am ascending to my Father and your Father, my God and your God.”
Now after He had ascended the first time would he not be defiled by allowing His disciples to touch him when he returned to them? Or were they cleaned and santified? He appears to them, eats with them, walks with them. Yet later when He comes to eal with Saul only a voice is heard. Paul could not see Him but only hear him. Paul was blinded.