\documentclass{article}
\usepackage{mfirstuc}
\usepackage{nameref}

\begin{document}

\section{Sentence-Case}
\label{sec:sentencecase}

\MFUblocker{\nameref}
\makefirstuc{\nameref{sec:sentencecase} section} /
\MFUsentencecase{\nameref{sec:sentencecase} section}

\end{document}