The Bad Batch (2016) by Ana Lily Amirpour

[Drunk Monk]

The amputated arm and leg, which you said were very convincing (and I agree), were done with in-camera effects.  Not post.  I still struggle to comprehend this.

I too, struggle with this. 

To its credit, this won the Special Jury Prize at Cannes and was up for the coveted Golden Lion.