You are gonna make my head even bigger at this rate, mate!
Considering the closest living relative of the Hawkstrider is the Plainstrider, aka the Cassowary, let’s take a look at some fun little things it can do.
Don’t let the neck-sticles fool you, this thing is a Dinosaur and it will mess you up. The talons on those feet are capable of severing limbs with a single kick, and have killed dogs, people and anything dumb enough to get near the Cassowary or, if you’re extra specially stupid, its chicks or try to feed it.
Cassowaries also have those lovely crash helmets which they use for running through the tropical rain-forests they call home, literally bashing their way between trees and through the undergrowth like an exceptionally flamboyant Raptor with a raging lust for brain damage.
Taking this to the Hawkstrider, and beefing it up as the Sin’dorei did to make a war-mount, we have something absolutely pant-soiling on our hands. Not only are those feet bigger and equipped with some massive talons, the heads lack the crash-helmet, but look at how a Hawkstrider runs. Head out, beak first. Unlike Cassowaries who eat fruit, nuts and the occasional terminally stupid tourist, the Hawkstrider’s beak is significant larger, stronger and curved.
That there is a murder beak. Big, almost bigger than the Hawkstrider’s head, thick and curved to a point, but not a tearing point. A stabbing point. Hawkstriders drop their heads level with their bodies and charge when they run. Sin’dorei warriors and rangers never needed a lance, their mount already comes with one, and if you’re agile enough to dodge, then out come those deadly bloody claws.
Did you know Australians lost a war against the damn Emus? Do you know who? Because the feathery fat-headed frakkers have all of their organs in one of nature’s toughest rib-cages. Everything else is just muscle. You have that thing bearing down on you as fast as a horse can run, with the agility of the Cassowary and every part of its body barring those ridiculous wings is capable of killing you dead. If that beak doesn’t punch a sword-sized hole in you, the talons will disembowel you or at the very least deliver a devastating blow, and even if you managed to dodge all that? The Cassowary is incredibly dense for its size, weighing a whopping 85 kilos (or 187 pounds for the 'Muricans) for its 190 cm (75 inches) tall frame. Something the size of a Hawkstrider might even be heavier than a normal riding horse, which adds even more penetrative power to its attacks.
You have several of those things kicking in a scrum, I don’t care how much regeneration your Loa gives you, you’re going to Bwonsamdi now.
Something to consider is that the Riding Sabers are based on a conglomeration of Tigers, Saber-Toothed Tigers and Jaguars. Two of these cats are notorious swimmers and climbers.
Ever wondered why Sentinels scare the 
out of people? Imagine you’re fighting expert guerilla warriors, and their favoured mount can climb trees like they’re nothing, and what is Ashenvale and the surrounding areas if nothing but gorram trees? A sentinel doesn’t need to swim across a raging river in full armor, she can just dismount, grab hold of her mount’s saddle and hold on as Lord Wubblins the Third just happily swims across with no problems and zero complaints.
Did you know cats can purr to heal themselves? Were you aware a cat purring on your body can actually accelerate your own healing process?
Suddenly every scarred Sentinel in my head got their ‘battle scars’ for going in for a belly rub at the wrong moment. Tigers in particular are, despite being rather solitary animals in the wild, when there’s plenty of food and no reason to fight, will gather in large groups, groom each other and even play. I imagine Riding Sabers are very much the same, but more so, and will happily curl up around their Sentinel both for comfort and as a display of affection.
Cats fight by biting at the throat, biting the back of the skull, and when in a fight with a predator of equal size, will actively grapple with their fore-legs and bite at each other’s faces, while kickin with their back legs. Domestic cats, this is mostly a display and causes minor injuries. Something the size and strength of a Riding Saber? You’re disemboweled with the first kick, assuming your skull wasn’t perforated by those giant fangs, or you weren’t immediately ripped open by one of those massive paws that somehow didn’t just snap your neck with a swipe.
That said, cat backs are not intended to carry that much weight for long periods of time, so I’d imagine Sentinels only ride their Sabers when they absolutely have to, or there’s something going on with the spines of a Riding Saber that strengthens the bones and ligaments in the spine to allow it to be ridden for a long period of time, but this would in turn affect the cat’s flexibility … that said, Riding Sabers trace their origins to the original Kaldorei Empire, when flesh-warping magic was widely in use, so there’s a good chance the Riding Sabers we see today owe their unique ability to be ridden as a mount to their ancient ancestors.
Kodos I’m not too sure on, the Tauren seem to love them and the Kodo is the Horde’s beast of choice when it comes to drawing wagons and carrying heavy loads, so I’d assume a domesticated Kodo is quite tolerant and friendly unless spooked, or heavily provoked.
That said, Kodos display both scales and fur, so I’d assume they’re some kind of Monotreme, like the Echidna and the Platypus?
Elekk, however, are definitely Elephants, and you know what the worst thing is about an Elephant? They’re damn intelligent. A Draenei rider probably doesn’t even need to direct their mount, it is smart enough to know friend from foe, strong enough to flip anything not bigger than itself with just a few seconds and that trunk is capable of a wallop in its own right, if not being useful for yanking an enemy rider clean off their own mount, if not breaking their neck or dislocating a limb in the process.
While the trunk is rather smaller and shorter than a real-world Elephant would possess, look at those tusks. Perfect for smashing aside anything in their way, especially with all that weight and momentum behind them, and that Saddle is more for holding on for dear life than actively directing the Elekk mid-charge. While not the most agile of mounts, the Elekk certainly boasts a staggering strength advantage, and like the real-world Elephant, has stamina for days. Need to flip a siege-tank over or punch a rather large hole into an enemy’s defensive line? Send in the Elekks, especially the armored versions which adds to the thick hide and plated heads of the Elekk with additional armor over the fore-legs and vulnerable sides.
Are we allowed to talk about how Elephant dung is one of the most prodigious fertilizers in the world? Or how Elephant milk is so super-dense with vitamins, calcium and mineral that we literally cannot metabolize it before it passes through our systems?
Suddenly, there’s no need to worry why Draenei are so gosh-darn built. All that milk …
This one is gonna be really brief, but anyone else remember Phlogiston? It was a type of rather common gas that, when done right, could be combined with a precise mixture of oil and water to create a fluid that dramatically increased the capacity of steam-driven engines, allowing steam engines to burn hotter and survive extreme pressure.
And best of all … it was cheap. A single vial of Phlogiston could allow a flying machine to function all day long … assuming you had the water to provide the steam to turn the mechanisms. Likely the engineers found a way to regulate this too, but we can assume most of the original models of Mechanostriders ran on Phlogiston-powered engines. It also explains why both the Alliance and Horde fiend for oil, since it is a vital component of the mixture, and water is everywhere, especially with Mages around. Cheap, inexpensive and plentiful, Phlogiston-powered Mechanstriders were likely all the rage … for a while.
The combat models we use as Players, however, probably run on something far more potent, likely a miniature version of the reactors that one powered Gnomeragon, likely some fusion of arcaneo-science and good old fashioned Gnomish Engineering, and draw their power directly from the ley-lines, or can refuel on a more potent mixture of fuels intended to give a far more potent effect than a steam-engine alone could produce.
That said, I am now very interested to know if the engines we see, Dwarven Steam-Tanks, Horde Demolishers, Horde Zepplins and Alliance Air-Ships still use Phlogiston engines due to the relative cheapness and availability of the fuel, or if they’re all running on actual fuel and magi-tech batteries?