His coloring looks like a blue with black head...steel blue w/black head...fairly common but he has an added kick of, looks like partial dragon scaling. If he is metallic, he could have copper but it could also be result of his partial dragon scaling (more than likely where saleslady got "dragon" from!). I can't tell his tail/fin type...more pics might help us to nail down more.
Thank you and congratulations on your wonderful save! Good luck and I hope you have many years filled with smiles and laughs with your new friend!
I agree, not a dragon but a dark blue w/black head. Depending on hi age, he could be plakat (have short tail), but if he is young (and the bettas sold at the "marts" are quite young), his fins could continue to grow until you've got a veil tail or HM....the way his fins lay now, I'd guess you have a young VT.