|laziness, impatience, and hubris|
"I heard the other day that he had rewritten eveything in ksh and deleted my work."
Quite a big surprise to me. I work in a place that Java and c are dominant, and they also have lots of ksh scripts. For every project I can decide the technical direction, I always require scripts to be done in Perl instead of ksh, and this is how Perl got introduced to the company, and slowly became popular. I believe that's the right direction. To me, Perl is a kind of programming language, but ksh is only a traditional scripting language that has very limited functionality.
Even under this direction, I will never ask anyone to rewrite exsiting ksh script in Perl, as that's a waste of time. We only use Perl for new scripts. So delete your stuff, and do a total rewrite sounds very stupid to me. Even if there might be certain things can be improved in your scripts, they should just fix it in Perl.
"Where should I go from here?"
Nobody else can judge better than you yourself, as only you know yourself and the place you work. Instead of learning for learning, why not just try to do more things in Perl, that's the best way to learn.
Also with the Perl knowledge you learned so far, come to this site more often, try to help people out, just as others helped you. Answering questions is also a good way to learn. Even give a bad answer and get corrected is a good way to learn.
Thought about it more, I actually have a question: when you said that they rewrote your Perl scripts (DBI) in ksh, what eactly did they do? (1) execute queries through something like SQL*PLUS (2) or rewrite the program in something like Java, and execute through ksh scripts? or ...