Realcent.org

I have a couple coins the local coin shop has asked me to find out about. I'm guessing ancient, but beyond that I don't have any idea of where to even start. Please help, and thank you! I put them in 2x2s for size reference. Normal scans below, with links here to higher resolution scans:
https://www.flickr.com/photos/49330253@N05/13894187181/sizes/o/
https://www.flickr.com/photos/49330253@N05/13894186931/sizes/o/

Amazing. It's JESUS.

I'm seeing stuff which is very similar to the first coin, but nothing which quite matches. I mean, I would assume what you've sent is not an exhaustive image list - it looks like there's even a 2-century span it could fit with! But I can't find more images which do fit. This one seems to have some additional design element(s), specifically on the obverse left. Also, they are all silver and this is copper. Again, I know it's not exhaustive... So just how varied/plentiful were these Medieval Venetian types? Would you feel fairly certain that it IS a 13th-14th century Venetian "Christ" coin?

This is fascinating. Also frustrating.