Ambush him from behind

A blue dragon might not be particularly powerful compared to other dragonkin. Their scales may not be as hard, or their claws as sharp, but what they lack in direct combat ability; they make up for in quiet maneuvering. Also while weaker overall physically, you surely can handle a single measley human.

With that in mind, you climb up onto shore and paw up behind the knight. The broad shoulders of his back face you as he looks around ahead of him for the danger he believes is forwards and not behind. He had just taken his first step out of the gatehouse when you tense up and prepare to pounce.Suddenly his horse outside the gate whinnies and the Knight swings around. You back off, but his blade clips your right front shoulder and blood splatters against the wall of the gatehouse.

"Damnable beast!" You growl in pain and irritation in dragontongue at your ambush being blown. Obviously his horse saw or smelled something that excited him.

The Knight releases a sadistic chuckle. "There you are Beast. Your head will decorate my mantle!"

He wastes no time pressing his advantage. His greatsword swings in your direction and you barely pull back before it hits you. This is bad. You are stuck inside the gatehouse with no room to maneuver or escape and you don't dare turn your back to him. He continues to swing at you and while doing your best to move out of the way, the blade clips your front legs and chest. You continue to back off looking for an opening and manage to get some claw strikes in, but the blows don't manage to pierce his armor.

You feel the sun against your tail and lower back and a brief glimmer of hope appears that you'll be able to get into an open area and back off when he overswings his blade. Lashing out with your powerful jaws, your teeth sink into the wrist of his sword hand. The Knight releases a pained shout and punches his mailed fist agaisnt the side of your head, but you do not let go and sink your teeth deeper. The metallic taste of blood coats your tongue and mouth.

Out of the corner of your eye, you see him pull a dagger out of his belt. He brandishes it for a moment and before you can react, he plunges it into your neck. A sharp pain pierces through your body and you howl in pain, letting go of his arm. The Knight shouts in victory and swings his greatsword and it collides with your neck right behind your head. A brief feeling of falling overtakes you before the darkness of **** takes you.

It would seem as if your head will indeed decorate his mantle.