Since you've used regex, why not take advantage of $regml() :

on @*:input:#:{
  if ($regex($1,/([+-])([vhoaq])/)) {
    if ($2 !ison #) { 
      echo 4 User is not currently in the channel. 
      halt 
    }
    mode # $+($regml(1),$regml(2)) $2
  }
}