The seem redundant if worn with a cuisse, Yet I see the two worn together all the time. Whats the point?

Well for one thing you have a huge gap between the cuirass and the Cuisse and even chausses an impact weapon can do a lot of damage to your leg

What Ben said. You need to be able to bend your legs where they meet the hip, and if you put the cuisse too high it will impede this movement. If you make the tasset too long, then it won't move properly, either. Put them together, and you have a very well covered leg.

You do see 2nd half of 15th german harnesses without tassets for this reason. On these the cuisses are multilamed up the entire leg and go well under the faulds. Unless this was done with the cuisses the tassets were still very important for the reasons Ben and Bill stated.

RPM

Ok, cuz it looked like the fauld and cuisse covered it, but I didn't think about movement, thanks.