Weapon dice multiplier

With Update 14, upper tier weapons in game, that previously had irregular damage dices (such as old Green Steel weapons and old Alchemical weapons) are updated in order to standardize them among various weapon types. This mechanic, called Weapon Dice Multiplier or Base Damage Dice modifier, is applied to weapon dice roll. It is shown on the weapon description window in the format of #[W], where # is the multiplier and [W] is the base weapon damage.
 * For example, "1.5[1d8]" would mean 1d8 is weapon specific dice to roll for base damage, and 1.5 is what is considered as the multiplier (1.5-1=0.5 is what is considered modifier).
 * If the weapon's base damage is multiple dice, such as a Falchion's [2d4], a Great Sword's [2d6] or a Great Crossbow's [2d8], then any modifier multiplies all dice within the brackets. So a +1[W] modifier to [2d8] makes that 2[2d8], etc. (Note that this is not the same as "4d8" - 2d8 are rolled as base weapon damage, and that is then multiplied by the preceding value. See Developer quote, below)

Weapon dice multiplier is applied to weapon damage before enhancement bonus and before critical hit multiplier. Spell buffs such as Deadly Weapons, and feats such as Point Blank Shot may have an impact on this value.

Randomly generated weapons
With Update 29, randomly generated weapons gain additional [W] depending on their minimum level:
 * Min Level 10 = 1.5[W]
 * Min Level 20 = 2.0[W]
 * Min Level 24 = 3.0[W]
 * Min Level 28 = 4.0[W]

Named / crafted weapons

 * Nightforge weapons from the Black Anvil Mines - 1.5[W]
 * Green Steel weapons - 1.5[W]
 * Alchemical weapons - 2[W]
 * Old epic ML20 named weapons - generally 2[W]
 * Epic Sword of Shadow - 2.5[W]
 * Cormyrian weapons - 2[W]
 * Drow weapons from The House of Rusted Blades - 3[W]
 * Relic weapons from Caught in the Web - 2.5[W]
 * Thunder-Forged weapons - 3.5[W]~4.5[W]
 * Epic ToEE Crafting weapons - 5[W]
 * Legendary Green Steel weapons - 5[W]
 * Other end-game named weapons - often 5[W]~5.5[W]

Feats

 * Point Blank Shot: +1[W] (ranged weapons)
 * Combat Archery: +1[W] (ranged weapons)
 * Improved Martial Arts: +1[W] (unarmed) or +0.5[W] (with ki weapons)
 * Past Life: Disciple of the Fist: +0.5[W] (unarmed)
 * Unarmed Strike: +0.5[W] to +2.5[W] (unarmed while centered) automaticaly earned at Monk levels 4, 8, 12, 16 and 20'', changed to +1 attack every 4 levels in Update 40.

Enhancements
Artificer
 * Weapon Attachment: +0.5[W]

Barbarian
 * Crazy Strike: +0.5/+1/+2[W] (after you score a hit with Cracking Attack)
 * Raging Blows: +1[W] (melee attacks while raging)

Fighter/Paladin
 * Shield Combat II: +1[W] (to equipped shields)
 * Vicious Shield II: +1[W] (to equipped shields)
 * Shield Champion: +1[W] (to equipped shields)

Monk
 * Way of the Tenacious Badger: +0.25[W] to +1[W] (when below 50% health)
 * Empty Hand Mastery: +0.75[W] (unarmed) -> enhancement was changed in U33
 * Touch the Void Dragon: +1[W] (unarmed)
 * To Seek Perfection: +2[W] (unarmed)

Rogue
 * Sniper: +2[W] (non-repeating crossbows)

Wizard
 * Shroud of the Zombie: +1[W] (unarmed)

Harper Agent/Halfling
 * Heroic Companion: +0.25[W]/+0.5[W]/+1[W] (to targeted ally only)

Warforged/Bladeforged
 * Weapon Attachment: +0.5[W]

Epic Destinies

 * Intolerant Blows: +1[W] (requires one use of Smite Evil, seems to add only +0.5[W])
 * Combat Brute: +1[W] (melee weapons when specific Action Boosts are active)
 * Improved Power Attack: +0.5[W] (Power Attack stance must be active)
 * A Dance of Flowers: +0.25[W] to +1[W] (any weapon while centered)
 * Dancing with Flames: +0.3[W] to +1[W] (Sun Stance must be active and requires Monk levels)
 * Avatar of Nature: a large bonus to damage based on size (Primal Avatar Epic Moment)

Spells

 * Deadly Weapons: +1[W]
 * Shillelagh: +1[W] (wooden quarterstaves) or +0.5[W] (every other wooden weapon)

Item Effects

 * Vorpal enchantment: +0.5[W]
 * Keen II and higher enchantment: +0.5[W] per level beyond I
 * Impact II and higher enchantment: +0.5[W] per level beyond I
 * Reinforced Fists: +0.5[W] (unarmed)
 * Greater Reinforced Fists: +1[W] (unarmed)
 * Dethek Runestone: +2[W] (while in Animal Form)

Guild Airship Amenities

 * Ninja Assassin: +0.25[W]