getting kicked by an extra-large horse is pretty bad
Important note: that's extra-large by medieval warhorse standards.
Destriers, also known as the "great-horse", are what we generally think of as the medieval epitome of horses. The thing a royal knights would ride off the tournament into battle alongside their king, clad in plate and colourful fabrics.
Those were about 14ish hands tall (yes, there an exists a unit dumber than the inch, and we thankfully only use it for horses)
More common than the Destrier were Chargers. Generally more suited for regular cavalry because they were more maneuverable (which is nice since most of the time you'll be fighting, not running in a straight line). Chargers were also smaller than a Destrier.
For those of you not into riding: in most countries today, anything under 14.2 hands is a pony (for competition purposes, it's complex). The noble tournament mount, pride of a professional knight, is about the size of a big pony.
A regular warhorse for the regular rider was about 1m35 tall (from where the neck meets the back, which is where you measure a horse).
And if you're thinking "wait a minute, isn't an armored knight way too heavy for a horse that small? Isn't that unhealthy?" Remember that these are warhorses. They do things that are MUCH more unhealthy, like going into battle. They would also have different horses to ride on their way to the battle.
Ah, well in addition to using a unique unit, you also measure a horse in a unique way. You measure up to the "withers", which is sorta kinda the highest point of the shoulders. So you get all of the neck and head on top of that 1.35m. measuring the top of a horses head is really very hard, because they tend not to cooperate if you tell them to stand up, and traditionally it's not a usefull number for pulling a wagon or riding.
Regardless, that is still small for a horse. An average modern riding horse for an adult is usually something like 1.55 at the withers, or ~15 hands.
An actually big horse, like a Clydesdale, can easily be 1.8m at the withers, and then there's an absolutely massive neck and head on top of that.