Oh my God no. Baseless Hollywood Bologna. A well trained armored and armed opponent would dice a bare knuckles fighter without a worry. When talking about a theoretical real life situations like this you have to throw out all anime and movie notions that a man in plate with be as slow as a turtle and clumsy. Generally speaking, if you go out in the field in plate and scale you are VERY likely to be well trained in moving about in it as well as know how to use your weapon effectively and ALSO how to use wrestling and grappling moves when it *did* get too close for comfort. As we should know from a plethora of old sword arts manuals from Germany and other parts of Europe, knighs were well trained in hand to hand combat as well; heck, half of their fighting moves were based on disarming opponents or wrestling them to the ground.
Hate to break your heart here, Sykes, but I've FOUGHT in full-armored plate. There's no anime or movie references in my knowledge of ancient armor.
If you've never had to wear the suit of armor... try to move with the joints... try to balance your own weight with that of your weapon (and shield, if you had one like me)... then you really have no grounds upon which to base your claim. Our study group had to practice for almost six months in the practice suits before being custom fitted for actual plate. In that time, we had to learn all of the basic (historically documented) combat strategies which could actually be attributed to knights. Unfortunately, this is a fairly small amount of information to go on... so really a lot of the practice was guess work on behalf of historians.
For those six months, we had to learn to balance a sword and shield... to use pole-arm sweeps... how to properly apply the use of a blunt weapon... all while not being able to raise your hand up high enough to scratch your head or wipe the sweat from your face. It was miserable, and awesome, all at the same time... but moreover, it hurts like hell.
Armor will wear you down -fast-. There's no Oblivion-style fatigue reduction perk for practicing in it. Even if you have the Endurance of a Roman God... the weight of plate armor, and the inflexibility of its joints will tax you until you're ready to drop. The lighter the plate, the longer you can fight... but the less protection it provides against a mace. It's a trade-off, no matter how you look at it.
When we finally got fitted for the real thing, it was much higher quality... and much easier to use... but you were still slow as all hell. Just trying to walk in a pair of armored boots was tiring... and I'd been doing it since early August. By the time February came around, and we got to do a few mock battles in our own armor, most of us had gotten good enough where we could keep on par in the guys who were using chain armor and leather with swords and shields. Almost. They still could move much better, because they didn't have to deal with the rigid plates not bending in the same ways the human body can.
An unarmored opponent using hand-to-hand tactics or a single short knife? We wouldn't have stood a chance. There is absolutely
no comparison in speed and reaction time between an individual in heavy armor and one who is unarmored. None. If you were lucky, you might see them coming before they could get to you and call for assistance.
Against two or more enemies, an unarmored hand-to-hand or short-blade user would have difficulty... but one-on-one, the favor is distinctly in favor of the unarmored opponent, every time.
That being said, I "killed" my fair share of footsoldiers in quilted armor and chain wielding daggers. It really all depends on the intelligence of the attacker... and whether or not they get the drop on you. Armor versus Unarmored has nothing to do with skill or power, and everything to do with speed and agility.
No anime or Hollywood physics here. Just plain-old-fashioned archaeology/anthropology nerd-dom.
(Bear in mind, of course, that I only had six months to practice. A knight would have had longer... but by the time six months were up, you basically knew how the armor could and could not move. The rest was up to skill, which always varies somewhat.)