Only Runic weapons that are made “exceptional” will provide the +4 damage in addition to the magic weapon bonus. So an exceptional weapon of force (gold runic) will provide a +9 dmg bonus (+4 exceptional and +5 force) equivalent to a normal vanq weapon.
Dull Copper: Durable Accurate (+5 Tactics) Shadow: Durable of Ruin (+1 damage) Copper: Fortified Surpassingly Accurate of Ruin (+10 Tactics and +1 damage) Bronze: Fortified Surpassingly Accurate of Might (+10 Tactics and +3 damage) Gold: Indestructible Eminently Accurate of Force (+15 Tactics and +5 damage) Agapite: Indestructible Eminently Accurate of Power (+15 Tactics and +7 damage) Verite: Indestructible Exceedingly Accurate of Power (+20 Tactics and +7 damage) Valorite: Indestructible Supremely Accurate of Vanquishing (+25 Tactics and +9 damage) Like @Arcanias said... If it is Exceptional. = Add +4 Damage
An exceptional agapite weapon of power is equivalent to a normal weapon of power (+7 dmg) with an additional +4 dmg bonus for being exceptional. That gives +11 dmg total, which is 2 dmg more than a normal vanq weapon (+9).