It's not possible to make the validity of a sacrament dependent on the state of grace of the priest (or deacon or other minister of the sacrament) because it is impossible to be morally sure whether another person is in a state of grace. A person with virtuous exterior may be proud as a pit-hag or a secret atheist or whatever. It has to be dependent on Christ acting --- His virtue and merit --- and not that of the human who is (however sincerely or fraudulently) acting in His name.
That makes sense, I would say.
We are all under grace, which God bestows on us LAVISHLY, not parceling it out through sacraments to the elect few.
The grace is accessed by faith through Christ, not sacraments.
Romans 5:1-2 Therefore, since we have been justified by faith, we have peace with God through our Lord Jesus Christ. Through him we have also obtained access by faith into this grace in which we stand, and we rejoice in hope of the glory of God.
And there is only ONE mediator between God and man.
1 Timothy 2:5-6 For there is one God, and there is one mediator between God and men, the man Christ Jesus, who gave himself as a ransom for all, which is the testimony given at the proper time.