I think the Most Important Thing we need to Remember, Is that in all scenarios There is going to be one less peasant. Either, Because he was the first one to charge, or the Knight hit him first. Either way, the Intimidation of having a person you probably knew for years die besides you is either going to make you fight harder, driving you into a blood frenzy, or make you run off like a sissy. OF course were not looking at the fact, that Metal Armor was made to deflect blows from Light weaponry, from my Experience, So that the Knight or other armored persons can focus on larger opponents, and breaking the lines of weaker troops. I.E. Knights would run into a group of Rather Un-armored Un armed militia men and just keep going, swinging there sword as they go. They probably were not looking to kill anyone really just cause mayhem and spread fear thru out that column of soldiers. So when a Knight comes charging at you full speed atop a war horse. Your either going to get out of the way, breaking formation and making you more susceptible to attack from all sides. Or your going to try and fight, Slowing your progress towards the Hypothetically advancing troops ahead of you.
So all in All, I think the Knight would probably lose, Think about it, He's against six opponents who probably have a good reason to be killing him, something along the lines of This is there last chance for survival and freedom. So If they decide they are going to die anyway, regardless of what happens to this one knight. and the best chance they have of living is to kill him, They will most likely band together with some semblance of military tactic. Also, Were talking peasants, PRobably farmers and other proffesions requiring lots of Upper body strength. And Assuming the weapons they carry are the tools they use everyday, they will be pretty effective swinging a hoe/scythe/ax around. So all in all I think the peasants may win.
Of course The only way the knight can really win, is causing the peasants to defect, and run. He will most likely not be able to kill all 6 of them with out either injuring himself to the point of uselessness or endangering his life more time's then he may be comfortable with.
We also didn't look into the possibility of the knight running, although slim, if he's all alone, who is going to know? Let alone believe a few turn coat peasants that either attacked him in the depths of the knight, or are probably schedueled to be killed anyway.