to avoid repetition u can use $iif() and u can use tokenize and use $1 untead of $regml(1)
and /ban -k to kick ban user

on @$*:text:/^(\!purge|[+-](f|m))\b/iS:#:{
  if !%f {
    inc -u4 %f
    tokenize 32 $strip($1-)
    if ($1 == !purge) && ($2 ison #) {
      ban -k # $2 2
      notice $2 message's been purged.
    }
    var %x $pos($1,+,1),%y $right($1,1)
    elseif ((%x) && (%y !isincs $chan(#).mode)) || ((!%x) && (%y isincs $chan(#).mode)) {
      mode # $1
      msg # $nick $+ , # is $iif(%x,now,no longer) $iif(%y = m,in slow mode.,in friends only mode.)
    }
  }
}