Your definition is not really the best even for text:
\DeclareRobustCommand{\frcshape}{\fontfamily{frc}\selectfont}
\DeclareTextFontCommand{\textfrc}{\frcshape}
Then \textfrc
will be much safer.
For having it also in math mode, define
\newcommand{\mathfrc}[1]{\mbox{\frcshape #1}}
and so
$\mathfrc{Abc}$
would give the expected result (which, in my opinion, is quite bad).
Note. Don't use \textfrc
in math mode if you load amsmath
, because it would try loading font sizes that aren't available.
Best Answer
There are several fonts that have cursive Es close to that in the sample.
Kunstlerscreibsch
http://www.font-db.com/font/kunstlerschreibschjoidbol/38809
Ecolier Court
(SIL license) http://www.fontspace.com/jean-douteau/ecolier