I understand blinding and hardening a little differently from most. I do not believe God ever determined anyone would be damned, including Pharaoh, or Judas. God simply knew they would reject the gospel, therefore it was not unjust to use them to further his plans.
Exo 3:17 And I have said, I will bring you up out of the affliction of Egypt unto the land of the Canaanites, and the Hittites, and the Amorites, and the Perizzites, and the Hivites, and the Jebusites, unto a land flowing with milk and honey.
18 And they shall hearken to thy voice: and thou shalt come, thou and the elders of Israel, unto the king of Egypt, and ye shall say unto him, The LORD God of the Hebrews hath met with us: and now let us go, we beseech thee, three days' journey into the wilderness, that we may sacrifice to the LORD our God.
19 And I am sure that the king of Egypt will not let you go, no, not by a mighty hand.
20 And I will stretch out my hand, and smite Egypt with all my wonders which I will do in the midst thereof: and after that he will let you go.
The Calvinist doesn't like the concept of foreknowledge, because it explains a lot. It explains how God can harden Pharaoh without being the cause of sin.
Did God say here he would cause Pharaoh not to let Israel go? No, it simply says God was "sure" that Pharaoh would not let Israel go. This is foreknowledge.
The same was true with Judas, God knew beforehand he would not believe and that he would betray Jesus.
Jhn 6:64 But there are some of you that believe not.
For Jesus knew from the beginning who they were that believed not, and who should betray him.
Does this verse say Jesus caused Judas not to believe and to betray Jesus? NO, it says he KNEW FROM THE BEGINNING who would not believe and who would betray him. This is absolutely foreknowledge of faith (or lack of).
The scriptures do say God hardened Pharaoh's heart, but they also say Pharaoh hardened his own heart.
I believe God simply knew that the more he commanded Pharaoh to let the people go, the more and more obstinate and stubborn Pharaoh would become. Many people are like this, I can think of certain speakers for political parties who will go nuts if you say something supporting their opponents, they are completely predictable. You can easily work them up into a tizzy.
Some people are such jerks, you just know what they are going to do in a given situation.