going "no warnings" of course is not an option for me

Why not? there is nothing wrong in disabling them, at least if you know why they are happening: 

@sorted = map{ $_->[0]} sort{
               no warnings 'numeric';
               $a->[2] <=> $b->[2]
          } map{[$_, split/sequence/]} @unsorted;

[download]

However, for this particular case and as already stated in other monks answers, it is easier to extract just the number.

Besides that, if you are concerned about the sort performance, you should try Sort::Key and Sort::Key::Radix: 

use Sort::Key::Radix 'ukeysort';
my @sorted = ukeysort { /(\d+)/; $1 } @unsorted;

[download]

In reply to Re: Schwartzian transform deformed with impunity by salva
in thread Schwartzian transform deformed with impunity by biohisham

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