Thanks for the compliment! I have a hunch you've either done the same or you're planning your own hunt. I'm just trying using Arokh as elevator for this level. I found four places where I was able to deliver some thumping to the pair. And because I'm DYING to tell my tale, I'm gonna give the details below as a spoiler. The last 5 paragraphs tell the locations I found and of a bug that I thought would ruin the hunt results.
When I got Demise and shot it, I was suprised it wasn't vampiric also. The f/x makes it look like it should do something 'evil'. At least you're able to deliver a good punch up close and not take any splash damage. Great bow for the close in work.
SPOILER ALERT --- This section details a few ways to kill Shaza and Tora. You may want to try the challenge by yourself first. Information below may spoil your adventure. It's not as difficult as shooting down two attack helicopters while in a mine field using a BB gun hiding behind a rock. It's a little easier.
Right after the cut scene, pop up to the level of the Upper Ruins and fly as close to the ground as possible to the entrance. Land and get thru the tunnel to the back area and turn into cover. Hop off Arokh, heal if needed and make a first base save. Equip a bow (or sword if you're into those pointy things) and run back to the first area near the entrance. Run past the second smaller alcove and trigger 2 skeletons. Run back to cover and kill them. Save.
Go back out to the small alcove staying close to the left side wall. This little corner right at the mouth of the entrance will provide just enough cover. You've got to really put your face in it to avoid damage. The right side may work as well but I preferred the left side. Try both and see which spot feels best for your style. Check and make sure you can see both dragons. Set your inventory so you can select the Bow of the Order and some other bow using R1. Equip the alternate bow. Save. It seems to me that the dragons will get closer if you don't carry the BOTA. After you get a lock you can change bows by using R1.
You can try to lure them in using an alternate bow but they probably won't get close enough for a target lock. Doesn't hurt to try. Aim at the edge of the cliff or the tree with Dragon Strike or Flame Talon and try for some splash damage. If that doesn't work you'll have to bait them. Strafe right to keep a straight path out and do a suicide run (probably) toward the dragon on the left. Try to keep your path straight. Avoid the breath attacks as well as possible. Use side flips to turn/dodge and try to keep the entrance centered behind you. You may have to use the right stick to 'look' directly at your target as it moves in order to get a lock.
When you get a lock, Rynn will start to swivel and point up and down following the dragon with the bow. As the world turns, use the direction controls to get back to that little corner and hide. Easier said than done. It's disorienting to use different buttons to move in the right direction as the dragon turns Rynn. I tried to keep the path out as straight as possible so it was easier to remember the way back. When under cover equip the BOTA. Make a second save state.
When you're pointed toward the entrance, slide to the right until you can see your target and let one fly. Be careful not to hit the wall and take splash damage. Slide left and put your nose in the corner. You'll see a couple of quick flashes when his breath attack hits the wall. You may even see some of the breath trail as it curls around. Keep an eye out for the second dragon. He may come in for bite at you too. Keep up the attack, saving as desired using a third save state. When the weapon lock breaks, you've just killed Shaztor or whoever. If you hurry out you may be able to see him fall from the sky, but watch your back. Heal and save to your third save state.
The reason for the three save states is because sometimes the second dragon is gone after your kill. If this happens you'll still have the original locked on second save for replay with both dragons. You'll have to try again and keep the second dragon interested in you while firing at the first one. Make a suicide run every once in a while. Run out and show yourself after one of your saves to make him feel needed.
After the first kill you can use the same method to kill Torza (whoever) or you could try a few other areas. The enclosed area to the left as you leave the tunnel has some good cover and columns to shoot thru. The back left corner behind the crates is fairly safe. Got my first kill there, but the second dragon was gone after I was done. Dammit. No third save state either.
Had an interesting 'ring around the rosie' around the broken rock farther left until I was hit by the second dragon. It's a challenging spot to play with a single dragon. Farther left, in the area where the Mithril Hammer is found, I had done a good bit of damage while hiding behind/beside the crate and barrels until hit from behind by a skeleton I didn't know I triggered. This happened my first time thru. Kill those guys first.
I didn't like the killing ground on the other side of the entrance very much. One side of the enclosed area there is bordered by a chasm so a dragon can be hiding below you. It gives them too much of an advantage. The very back wall will give you some cover though. But you may like the challenge. Then there's the tree in front in case you're daring or crazy.
You could always go out and play with both of them at once if you want a real challenge. I'm sure there are other ways to kill the buggers, but I'm ready to move on. If you find some good places or other methods to use, pass along the news.
After the dragon hunt I ran across a bug. Left Arokh parked inside and went thru the lower ruins. When done Arokh was already outside. When mounted he refused to fly until I took him back inside and out again. Just a little flight ceiling error.