Why is it everytime I discover a new word wall guarded by a dragon, it's always the weakest default dragon? After I clear the area, return 5 days later the dragon actually gives me a fight, since it leveled up to my character which is great!

Really, I just discovered a new word wall I never been to only to have a default dragon guarding it instead of a frost or elder. I just sat back and watched Mjoll Lioness do a pretty cool kill animation on it while not breaking a sweat too.

When I find new word walls that I haven't been to at level 37, guarded by a default dragon, its like fighting a mudcrab. Why doesn't it spawn a leveled up dragon instead, when I find these new word walls? Instead tough dragons spawn to my level days later. That defeats the purpose of having a challenge to receive these new powers.

I encountered a Blood Dragon on a Word Wall I had not previously visited, so default dragons aren't all that are spawned.

That is just your luck. I have found a legendary dragon at Shearpoint recently and it was my first visit.

My last game I was getting Elder Dragons at word walls. Can't remember if I got anything higher than that, but I've had some FIERCE fights with dragons guarding the walls.