Armors and holdables have five 'factor' bits wich can be set, in
addition to three attribute bits (A, B, and C).

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Holdables

The attribute bits combine as follows with the handedness bits in the
equip bits field (1 = Pri, 2 = Sec, 3 = Both). Attribute C is used for
damage calculations and is explained below:

1-- Standard primary-hand weapon (mace)
1AB Parrying primary hand weapon (longsword)

2-- Standard secondary-hand weapon (hand axe, dagger)
2A- Non-weapon secondary hand item (torch, wand)
2-B Parrying secondary-hand item (shield)
2AB Parrying secondary-hand weapon (main-gauche)

3-- Standard two-handed weapon (halberd, quarterstaff)
3AB Parrying two-handed weapon (claymore)

For weapons, the factor bits determine damage dice, as listed in the
following algorithm. Damage dice are limited in the following way: for
each of the following attributes, the top bit is taken away: not
two-handed; secondary; parrying. Thus, a two-handed weapon can have
all five bits set. A secondary parrying weapon can have only the
lowest two factor bits set. A primary standard weapon can have all
but the highest bit set, as can a parrying two-handed weapon.

Damage is determined in the following algorithmic manner:
  1) The factor bits are actually a binary number n, which is in the
     range 0-31, which is then doubled. If n is still less than
     twice the number of bits b, n is raised to be twice b.
  2) If attribute C is set, b = b - 1.
  3) (s, r) = divmod(n, b). bds+r is rolled for damage.
  4) Examples:
       C b = 2, s = (0b00010 * 2) = 4     Roll: 1d4    (lowest)
         b = 2, s = (0b00011 * 2) = 6     Roll: 2d3
       C b = 3, s = (0b00110 * 2) = 12    Roll: 2d6
         b = 3, s = (0b00111 * 2) = 14    Roll: 3d4+2
         b = 4, s = (0b01101 * 2) = 26    Roll: 4d8+2
         b = 5, s = (0b10010 * 2) = 36    Roll: 5d7+1
         b = 5, s = (0b11111 * 2) = 62    Roll: 5d12+2 (highest)

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Wearables

For now, the attributes are unused for wearables.

For armor, the factor bits determine damage absorption. The lowest bit
is 5% absorption. The next is 10%. The next 15%. The next 20%. And the
last 25%. The absorption for all bits is added together. Therefore, the
highest possible absorption is 75%.
