Thank you all for your comments.
dennee,you just tripled what I knew about these swords, thanks very much!
Tom:The blade does seem to have a differentially hardened edge and thats a very big reason I wanted to etch it,I doubt the pattern will be great but it will stand out much more than if its not etched.
As to etching the blade,and damaging patina.I rarely leave any 'patina' or anything else on the blade,my goal being to keep my swords in as close to original condition as possible.I think the etch among other things actually helps prevent the blade from rusting and in the proccess of the etch the acidusually cleans the rust out of the pitting in the blade leaving it virtually free of all rust.Further more,Im careful when wetching to not over do it,I generally use lemon juice or very very dilute muriatic acid,like tom said if etched lightly it doesnt take much to take it off.