@list= sort {    @$a <=> @$b
              || ... secondary criterion ...
              || ... tertiary criterion ... 
            } @list;

##</code><code>##

$a->[-1] cmp $b->[-1] # untested

##</code><code>##

@list= sort {    @$a <=> @$b
              || $a->[-1] cmp $b->[-1]
            } @list;