Night Ninja said:
M&B doesn't lack in 'combat moves'.
And considering the lack of evidence in the historical record of hitting other people with pointy metal objects while falling from great heights, we can safely dismiss this as stupid bull**** nicked off lawnmower simulators and hack and slash RPGs.
I don't see why we would need to crack out the history books on this one, it's classic Newtonian physics. Basic Newtonian physics have pretty well stood the test of time, quantum physics notwithstanding.
Speaking in terms of physics, if we are talking about a jump from level ground, you are talking about the force your legs can generate pushing you upwards until an equal amount of force from gravity stops you, and another equal amount has you descending with the same amount of force when you touch the ground - it's basically the same amount of force you'd get if you simply used all that leg power in an uppercut. The only advantage in the jump attack over an uppercut is that you'd get the ability to swing your weapon in an overhead arc, as well, which, with weapons that use a lot of leverage, means that your weapon is also benefiting from gravity, instead of having to oppose it, the way it would in an underhanded arc.
Hence, a weapon with a short or no haft, like a knife, would have no noticeable difference between jump attack and uppercut.
A poleaxe, meanwhile, would probably have a fairly large difference. If you take a look at the way that people chop wood with a long axe (which is wholly inappropriate for combat unless the enemy is already on the ground, and you are going for an "execution" style of attack)(in fact, the maneuver I am talking about is exactly the same one they historically used in executions by axe) then the motion they use is actually almost jumping, itself. That said, actual jumping while swinging an axe also completely throws your balance to the wind, and would make your attack wildly inaccurate and make you incapable of handling the recoil when your axe actually hit something, which could easily knock you off your feet.
Jumping off a 3-story building and landing on someone
will do more damage to the person you land on than jumping from right next to them and colliding with them, that's simple fact. Again, it's suicidal to try, but it will do more damage to whatever you land on.
Also, I rather wonder why something like bows/crossbows/thrown weapons are not brought into this discussion - unlike bullets, slower-moving and heavier arrows/bolts/javelins/axes will lose a considerable amount of force over distance, and can gain a significant amount of force from gravity. Firing from up on castle walls gives you 30 feet's worth of gravity's assistance in the power of your arrows. Firing from the ground up to the castle walls means that a portion of your power is spent struggling against 30 feet's worth of gravity.
Unlike modern combat, where having the high ground is generally advantageous just for the fact that it's easier to take cover, high ground with pre-gunpowder ranged weapons should have significant advantages in the force transferred by your weapons.
As Rapier17 says, jumping around is stupid and leaves you vulnerable, but that doesn't mean that the "realistic" thing to do is ignore it entirely. As I said before, the realistic thing to do is show players
why it's so stupid, and let them lose all balance and get knocked to the floor and hurt themselves when they try something stupid.