I had the same problem with the regular size thoth--it is much too small when cut. After I had cut it, I loved the pictures, but it felt miniscule in my hands. So I traded them off, and luckily someone was nice enough here (thanks smokey!!) to trade me the big Thoth.
All I used was a pair of scissors (not all that sharp) and a corner trimmer (a must if you don't want to poke yourself). A little time and focus of cutting along the edge of the card and I was satisfied with an adequately close cut, even without machine. They are not as perfect as when I got them, but when I shuffle, I don't even notice (and its actually one of those things that gets to me if it it too off). It seems like its used, not cut unevenly.
Even though you are not a machine, it doesn't mean that using scissors on a deck will leave you with a botch. There's not really anything to be afraid of.