This is soo sad-
The architect you spoke to most likely told you Helvetica because it's a clean looking sans serif. The lettering architects master is learned because it is also clean and easy to read (as far as handwriting goes). The "industry standard" for architectural software is AutoCAD, and it ships with two and written TT fonts, CityBlueprint and Country Blueprint. Country Blueprint is a little sloppier. If you want to use this on a card, pick up a copy of Francis Ching's book Architectural Graphics, learn how to write like that, practice, draw up your card and scan it. These fonts aren't used by a single reputable architect. You have a wealth of resources before you, don't rip off someone's handwriting.
