I did not read through all the posts so I’m sorry if I am stating something someone has already said but salvific power does come from God. What ever abilities Mary has comes from God. Jesus is the one who redeemed us. Mary co-operates with that redemption by interceding for us. When we pray the Hail Mary we are asking for her to intercede for us “now and at the hour of our death” and so because of her great love for us and her obedience to God, that is what she does.
Also, God is love. God wants all to be saved and He listens to prayer. As evidenced at the wedding at Cana, He listens to the Blessed Mother’s prayers but all of us can pray for someone now and at the hour of their death asking God to have mercy on that person’s soul and spare them from the fires of hell.
Our Lady asked us at Fatima to pray for the conversion of sinners and to do acts of reparation, or penance, for sinners.
She gave us this prayer to be included in our rosary:
Oh my God forgive us our sins. Save us from the fires of hell. Lead all souls to heaven, especially those in most need of thy mercy.
Mary and Jesus have a special relationship as Mother and Son. She does not ask anything outside of her Son’s will but at the same time when she is asking according to His will, her prayers are very powerful.
God bless.