Well, this is interesting. I'm a bit worried at how quickly Harry has learnt swordfighting, but I suppose he could have gotten the mental aspect ironed out in limbo and then practiced since then. Great premise, great work, though you've done the cliche 'respect goblins and they're great!'. The goblins are a warlike race who like nothing more than to cause misfortune to others, primarily physically but finacially as well. You've made them violent, true, but I think you should demonstrate their propensity for war. It is what they're best at after all.
Anywho, this is a great story and I very much enjoyed it so far!
Don't worry about it. No SUPER-HARRY here. He's only learned enough to protect Amelia. Like you said, he has the knowledge, and he's practiced his tail off, for the past week. While not nearly enough, he only needs to use it the once. Look at Ralph Macchio.
Never fear, He's gonna need lots of practice to get to where he needs to be.
Goblins. I disagreed heavily with book seven's revised description of the goblins. Until then, they demonstrated the basic aspect of a clannish warrior guild. In seven, they became the traitorous backstabbers, out only for themselves, as personified by Griphook.
While they are warlike, I see them as a combination of Feringi and Klingon. they have the rigid social and moral/ethical code of the Ferengi, they also have the Klingon-like wherewithal to enforce it. Harry has earned their respect not only by bringing to light a major violation of that code, but also by being willing to face one of their warriors -as a goblin-, and killing him in a fair combat.
As to their propensity for violence, I think Voldemort is footing to discover that aspect of the goblins floor himself.
I'm glad you are enjoying the story; Please keep writing the insightful reviews. I like to see reviews from people who have questions.