Penetration:
- Bolters, the armour-piercing rocket rounds we all know and love, have Pen 2. Every other game has given them Pen 4.
- Meltaguns, the weapon designed for melting through the armor on a tank, have Pen 3. Contrast that with the Pen 12 they have in Only War.
- Power Weapons, which can cleave through tanks and Power Armour with ease, now have Pen 3. Contrast this with their usual Pen 9.
- Eviscerators, the oversized chainswords wielded by the fanatics of the Ministorum, have the highest Penetration value in the system, at Pen 4. Other than being erroneously described by FFG in the past as having a Power Field, Eviscerators have no history of being especially good at shearing through armour.
Armour:
- Cloth Robes have 3AP on the body and 2AP on the limbs. Apparently, the average burlap sackcloth is too thick for a Bolter's penetration to fully handle.
- A Manufactorum Coverall - a worker's uniform - offers 3AP to the limbs. The average worker of the Imperium is apparently wearing body armor.
- Enforcer Armour, which has been a form of Carapace in every fluff ever, is weaker than basic Guard flak, at 3AP across the board.
- Flak Armour no longer has a bonus to resisting explosives damage, though this may be due to Explosive no longer being a damage type.
- Carapace Armour is essentially the same as Flak, save for a thicker helmet and chestplate. I guess Storm Troopers don't get the good stuff after all!
- Light Power Armour, the sort worn by the Battle Sisters of the Adepta Sororitas, now has 6AP for the chest and 5AP everywhere else.
This is just all over the place. Values that have been the same through every gameline - Dark Heresy, Rogue Trader, Deathwatch, Black Crusade, and Only War - have been lessened for no reason. Cloth robes now offer the protection of Light Flak, Enforcer Carapace Armour is now worse than the Flak worn by common Guard infantry, the Carapace worn by Storm Troopers is little better than Flak, and Power Armour is somehow worse than the old Carapace!
A bolt shell, designed to punch through armour with ease, is now weaker than a mundane rifle round and cannot pierce a sackcloth robe. It's worth repeating; the guns carried by Space Marines cannot ignore a sackcloth robe . Commissars must execute errant Guardsmen by shooting them three or four times, I suppose.
Even worse is Melta. These weapons exist "to cut through armour plate and heavy bulkheads alike," according to this very rulebook, yet don't have enough penetrating power to get through the armour worn by a basic infantryman. Melta weapons have been described as "turning a Space Marine in full Terminator Armour to slag in a single blow," yet are not actually capable of injuring a civilian groundcar (30AV on the Front facing).
Or they might ignore vehicle armour completely, which is weird.
Power Weapons are the melee equivalent of Melta, designed to cut through almost anything. Yet they, too, are incapable of piercing the almighty Flak armour. Meanwhile, a fat chainsword is better at penetrating armour than any other weapon known to Man.
Who wrote these rules, and why are they employed? Have they ever read a single word about what they are building mechanics for or just guessing at random?