Although the sort function is un-glamorous and not very fast, there are times when it is adequate for the task at hand:

use strict;
use warnings;

my @array = (
    'Item1 - 2 foo, 2 bar',
    'Item2 - 16 foo, 8 bar',
    'Item3 - 0 foo, 1 bar',
    'Item4 - 1 foo, 3 bar',
    'Item5 - 4 foo, 12 bar',
    'Item6 - 1 foo, 2 bar',
);

@array = sort {get_bar($b) <=> get_bar($a)} @array;

print "$_\n" for @array;

sub get_bar {
    my ($line) = @_;
    my ($bar) = $line =~ /, (\d+) bar/;
    return $bar;
}
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There is no doubt that one of the transform methods would be much faster, though.