A guillotine is probably your best bet. It's strong enough to cut through a lot of papers with one quick slice, and there's nothing to get dull. The "blade" is not really a blade. It cuts by rubbing metal against metal.
I have two old heavy wooden ones purchased years ago at garage sales. One is 12" and one is 16". I don't know if the new plastic ones are as durable.
I have several trimmers as well. The rotary ones are more versatile since you can use interchangeable blades of different styles.