Revelation says every eye will see him and those who pierced him. As we know, Revelation is written in signs and symbols. Those who pierced him is alluding to the execution of Christ when the Roman soldier pierced the dead Jesus with a spear. Jesus will be pierced again at the conclusion of the parousia when all of his brothers are killed, as Jesus said 'you do it to these, my brothers, you do it to me.' The enemies of Christ will "see" Jesus in the sense they will know who they are fighting against and who is going to execute them. No one will imagine they are being attacked by Martians or Vishnu or some demon. Everyone will know that the Jesus, who is the son of Jehovah, not Christendom's jesus, is the Lord they have attacked.
Matthew 24:30 states: "Then the sign of the Son of man will appear in heaven, and all the tribes of the earth will beat themselves in grief, and they will see the Son of man coming on the clouds of heaven with power and great glory." Notice, it says the "sign of the Son of man will appear." What form that sign will take is unknowable. But, as far as seeing Jesus "coming upon the clouds of heaven," that is symbolic. Daniel 7:13 states that the Son of man is coming on the clouds of heaven. Clouds denote invisibility. When Jesus ascended to heaven he was taken up into the clouds and at that point disappeared from human view.