I'm not sure about a groove, but I can't figure out whether it's curved, as the reflection suggests in pic 4 or flat, and tapered to an edge (like pic 5).
For some reason I think curved. I mentioned in the other sword thread that I actually got quite close to this sword at a Planet Hollywood in Toronto or Montreal, and I'm pretty sure it was curved, but I can't find the pictures I took of it, so I can't say for sure.