perl -w -MData::Dumper -e '
@old = ( "10.5 AA", "9 AC", "2 BB");
%orcish = ();
@new = sort {($orcish{$b} ||= ForceFloat($b)) <=> ($orcish{$a} ||= ForceFloat($a))} @old; 
print Dumper \@new;
sub ForceFloat{
    return $_[0] =~ /(\d+\.*\d*)/ ? $1 : 0.0;
}'