Perl project review - Word counter
Use lexical filehandles instead of typeglobs (read here for more about why; the biggest problem with typeglobs is that they are global in scope).

open (my $handle,'&lt;:utf8', $file) || die "wrong filename";

You should close your filehandles sooner rather than waiting til the end of the program, if possible. For example, there's no reason to keep HDB open after its contents have been read into memory.
Consider changing @db to a hash, then using exists to check whether a word is in the exclude list. This should be faster than looping through the array (depending on how many words are in the exclude list and how often a word will be in the list). Since case is not important, you could call lc or uc before testing.

If you want to keep it as an array, then consider exiting the loop using last once the first match is found.
You sort the keys of %wordlist twice using the same criteria. Consider storing the sorted list in a new variable.