Gawain is a special unit in Stronghold Legends and only available to those users who are currently playing as the Arthur faction. He is recruited from The Round Table, and costs 500 gold and 100 Honour. You can find out ways to generate Honour in the game here.
His general skills and abilities mirror that very much of a standard Knight. His attack strength is virtually identical to that of a Knight in standard combat as well- in straight out combat between Gawain and a Knight, it's essentially the unit that strikes the first blow that will win.
By default, Gawain will be mounted when you purchase him from The Round Table. You can dismount him from his horse by selecting him and then clicking on the "dismount" icon.
Once mounted on a horse, any enemy units must first kill the horse before they can attack Gawain himself, so there are great advantages of doing so, besides Gawain moving a lot faster. The horse alone takes 2 Crossbow bolts to kill.
If the Horse is killed or you dismount Gawain, you can mount Gawain on another horse, but must wait for a short "recharge" time before this button becomes available again. To do this, select Gawain and then click on the "Mount horse" icon. Note that by mounting Gawain, like any unit, it will cost 20 Honour. Once you have attempted to mount him, a horse will instantly appear and he will automatically be mounted.
You can only have one Gawain unit at any time. If he is killed, you will instantly be able to purchase another Gawain unit from The Round Table again. Like all ground units from The Round Table, Gawain has a special power, in his case called Heavenly Shield.
This special power will protect all units within a certain vicinity from aerial attack, but this does not extend to ranged units on the ground. This is a massive help to many of your units in protecting them Dragons, White Witches or other aerial units who often pick them off with virtually no resistance of any kind. Note that Gawain must be close enough to the units you wish to defend to be able to use this power.
The power will only last for a certain amount of time, but the player who is attacking you will likely move their units away for the duration you are using this power. If one of the attacking units is a Dragon, this power will help you significantly as it will decrease the amount of damage the Dragon gives your units while it is still on the map.
You can activate this special power by left-clicking on the orange shield icon on the right side of your screen, and right clicking on the map where to use it. It can only be used somewhere within Gawain's range already, and once used, it will require a "recharge" time. During this, the green line around the outside of the orange shield icon on your screen must reach all the way around to the start before it can be used again.
This icon is only available while Gawain is alive, so if Gawain dies or you have not yet recruited him, you must recruit another Gawain from The Round Table again in order to use it. Only he has the ability to use this power.
However as Gawain is so similar to a Knight, the same weaknesses also apply to him. Without use of his horse, he is a very slow moving unit. He can easily get overwhelmed by defence systems such as Burning Logs, Ballistae or pitch ditches. And he can also very easily be picked off by ranged units, frozen by Ice units and have his health sputtered away over time by persistent attacks or fire. This is primarily due to the fact he moves so slowly.
The only real exception to Knights and other slow moving units is the fact that Gawain can defend himself and other nearby units against areial attack, providing his special power is fully re-charged and ready to be used. Note that while Gawain is using his power he cannot move or perform any other action, although you can move other units in and out of the aerial shield which Gawain creates. Archers and other units can still attack units beyond the boundaries of this protection.
Gawain will also struggle against units such as Frost Giants, even whilst mounted, simply because Frost Giants are so powerful and can cause an enormous amount of damage. It's therefore extremely important to protect him well to prevent this from happening, particularly if the enemy is playing as a different faction with access to more advanced units and magical powers, as most of these are not limited.
Tip: Gawain's power is particularly useful if you're caught out in the middle of nowhere moving your army to a siege point or some other location, attacking an enemy castle, or defending your own. His aerial protection can save many units from being slaughtered and can delay or stop aerial attacks altogether often moving attacking enemy units on to different locations. Use this power wisely.