Questions About Medieval Weapons/Armor

[Weewum]

If a Knight, Man at Arms, or plain old cavalry, charged with a Later-Period lance (The thick ones) it would be couched, but, if it failed to break, could it break the user's arm?

[Teeth]

It was braced under the shoulder, effectively supported by the entire upper body. I'd say his body would take quite a blow, but he should be fine.

[Prinz_Karl]

Generally they didn't take damage from thrusting the lance in the enemies body. If the lance stays unbroken the force the rider has to afford is just the one to push against the enemy body and the cantle of the saddle provided enough support for the rider, also the body and the arm of the rider weren't all stationary they could as well absorb the energy of the thrust. So it shouldn't have hurted him much.