const int alt_weapon = mon->inv[MSLOT_ALT_WEAPON];

    if (weapon == NON_ITEM)

    if (weapon == NON_ITEM && alt_weapon == NON_ITEM)

    item_def& wpn(mitm[weapon]);

    int slot;
    do
    {
        slot = (coinflip()) ? weapon : alt_weapon;
    }
    while (slot == NON_ITEM);

    item_def& wpn(mitm[slot]);