Perhaps the definitive reference for this sort of thing is in the standard Perl docs: perldsc (Perl Data Structures Cookbook). After you read and understand that, you should be on your way. For some light relief, some sample code to crudely dump ... then "pretty print" your hash of hashes:

use strict;
use warnings;
use Data::Dumper;

my $weapons_ref = {
  dagger     => { cost => 8,  damage => 4, armor => 0 },
  shortsword => { cost => 10, damage => 5, armor => 1 },
  warhammer  => { cost => 25, damage => 6, armor => 2 },
  longsword  => { cost => 40, damage => 7, armor => 0 },
  greataxe   => { cost => 74, damage => 8, armor => 0 },
};

print Dumper($weapons_ref);

# Print by hand so it looks a bit prettier. :)
for my $weapon ( sort keys %{$weapons_ref} ) {
  printf "%-14.14s\n", $weapon . ( '-' x 20 );
  for my $attr ( sort keys %{ $weapons_ref->{$weapon} } ) {
    printf "  %-8.8s:%3d\n", $attr, $weapons_ref->{$weapon}{$attr};
  }
}
[download]

which produces:

$VAR1 = {
          'dagger' => {
                        'cost' => 8,
                        'armor' => 0,
                        'damage' => 4
                      },
          'greataxe' => {
                          'damage' => 8,
                          'armor' => 0,
                          'cost' => 74
                        },
          'warhammer' => {
                           'armor' => 2,
                           'damage' => 6,
                           'cost' => 25
                         },
          'shortsword' => {
                            'damage' => 5,
                            'armor' => 1,
                            'cost' => 10
                          },
          'longsword' => {
                           'cost' => 40,
                           'damage' => 7,
                           'armor' => 0
                         }
        };
dagger--------
  armor   :  0
  cost    :  8
  damage  :  4
greataxe------
  armor   :  0
  cost    : 74
  damage  :  8
longsword-----
  armor   :  0
  cost    : 40
  damage  :  7
shortsword----
  armor   :  1
  cost    : 10
  damage  :  5
warhammer-----
  armor   :  2
  cost    : 25
  damage  :  6
[download]

I leave summing by cost and other attributes as an exercise for the reader ... just in case it's a homework question. :)