Arcus missile launcher

"Attacks made with the Skyfire Special Rule ignore penalties when attacking Flyers."
A Hit Test made for a Weapon with the Skyfire Special Rule ignores any Rule that would require attacks made targeting an enemy Unit that contains nay Models with the Flyer Sub-Type to be made as Snap Shots. Instead such an attack makes a normal Hit Test using the Ballistic Skill Characteristic of the attacking Model - this includes attacks made as part of any Reaction. A Unit that includes any Models with any Tactical Status may not benefit from the effects of this Special Rule.

"A Weapon with the Armourbane Special Rule counts Glancing Hits as Penetrating Hits."
When making Armour Penetration tests for an attack with this Special Rule, a result that is equal to, or greater than, the target Armour Value inflicts a Penetrating Hit. A Weapon with this Special Rule can never inflict a Glancing Hit, and any Rule that would force them to do so instead inflicts a Penetrating Hit.

"Weapons with this Special Rule are better able to utilize it for intercepting new arrivals on the Battlefield."
Each time a Model makes a Shooting Attack as part of the Intercept Advanced Reaction, it's Controlling Player can select a Weapon with this Special Rule for that Shooting Attack, even if it is not a Defensive Weapon.

"Attacks made with the Blast (X) Special Rule use a Blast Marker to determine how many Hits are caused."
When making attacks with a Weapon that has the Blast (X) Special Rule, before any Hit Tests are made, a Blast Marker must first be placed to determine how many Hits may be inflicted by the attack. The Player making the attack must place the Blast Marker indicated in brackets as part of the Special Rule so that the hole in the middle is entirely over the base of any one model in the Target Unit. Once the blast Marker has been placed, the Player making the attack must make a Hit Test for the attack, and each Model from the Target Unit that is fully or partially under the Blast Marker will suffer 1 Hit if the Hit Test is successful.

*Hits on Other Units*
If any Models form Units other than the Target Unit are fully or partially covered by the Blast Marker, then a new Fire Group must be created for those Hits and set to one side. Continue resolving the Shooting Attack on the original Target Unit, and once that Shooting Attack has been completely resolved begin a new Shooting Attack to resolve those additional Fire Groups generated for Units other than the original Target Unit.

If the Hit Test is unsuccessful then no Hits are inflicted and the Player making the attack must make a Scatter Roll for the Blast Marker (see the Rules for Scatter in the Warhammer: The Horus Heresy - Age of Darkness Rulebook). Once a Scatter Roll has been made for the Blast Marker and it has been moved, one Hit is inflicted on a Unit for each Model from that Unit that is wholly or partially covered by the Blast Marker.

"Weapons and other attacks that have the Panic (X) Special Rule have a chance of inflicting the Routed Status on the Target Unit."
If a Shooting Attack made for a Weapon or Model with this Special Rule inflicts one or more wounds on a Target Unit, regardless of whether any Damage is inflicted, that Target Unit must make a Leadership Check in the Morale Sub-Phase of the same Player Turn. If this Check is failed then all Models in the Unit gain the Routed Status, if the Check is passed then there is no further effect. The value of X attached to this Special Rule is applied as a negative modifier to the Leadership Characteristics of Models in the Target Unit when making Checks caused by an attack with this Special Rule. If the attack includes multiple Weapons with different variations of this Special Rule the modifiers do not stack - use only the greatest modifier.

"Weapons with the Shock (X) Special Rule have a chance of inflicting Statuses on Vehicles even if it does not penetrate their armour."
When making a Hit Test for a Weapon with this Special Rule against a Target Unit that includes any Models with the Vehicle Type or Walker Type, the result of the Hit Test before any modifiers are applied must be checked. If any Hit Test for a Weapon with the Shock (X) Special Rule results in a '5' or '6' before any modifiers are applied, then all Models with the Vehicle Type or Walker Type in the Target Unit gain a Status at the end of Step 11 of the Shooting Attack process or Step 10 of the Initiative Step process. The Status gained in indicated by the value of X attached to that variant of the Shock (X) Special Rule. If the Model already has the stated Status or the attack would apply the Status multiple times there is no additional effect and this Special Rule never causes a Model to lose Wounds or Hull Points. Hits inflicted by a Weapon with this Special Rule must still have Wound Tests or Armour Penetration Tests made for them, and are not discarded if they trigger this Special Rule.