Other than used for effective breaking of branches for feeding, the Black Rhinos horns are essential for self-defense and territorial battles.
When faced with threats, black rhinos use their horns to fend off attackers or protect their young. Despite being made of keratin (the same material as our hair and nails), these horns are strong and sharp enough to penetrate even the thick hide that rhinos have.
In that respect, dehorning some members of a black rhino population while leaving others intact should be carefully considered in the light of disrupting Black Rhino ecology and the likelihood of increased mortality through territorial fighting.