I've carried different knives into Disney World for years without even a comment. Just be low-key about it and you're likely to never even hear a peep from them. I've seen other guys walk right in with obvious large folders visibly clipped on their jeans pockets, but I at least drop mine down inside my pocket or inside my waistband. I get a lot of use out of a small Swiss Army knife throughout my Disney trips, especially the scissors.

About the fingerprint thing: I believe you can decline to have your finger scanned and present photo ID instead. If you ask nicely you might not even have to present ID.

Disney cast members are usually pretty accommodating and will bend rules for you if you ask nicely and look like you're just there having fun with your family (and spending money).