  We explicitly determine the high-energy asymptotics for Weyl-Titchmarsh
matrices associated with general Dirac-type operators on half-lines and on
$\bbR$. We also prove new local uniqueness results for Dirac-type operators in
terms of exponentially small differences of Weyl-Titchmarsh matrices. As
concrete applications of the asymptotic high-energy expansion we derive a trace
formula for Dirac operators and use it to prove a Borg-type theorem.
