I tried to test them but I have no real scientific results and today I can't even load the saves. 
Can Vandal stack with other skills, its says attacks but does not specify Two Handed Attacks or Melee Attacks or Ranged Attacks.
Two Handed - Vandal 225
Your attacks ignore 25% of enemy's armor. in game text
This perk correctly multiplies effective enemy armor by 0.75 (-25%) with all weapons. Source Bannerlordperks.
One Handed - Chink in the Armor 250
Your one handed melee attacks ignore 10% of enemy's armor. in game text
This perk correctly allows the hero's one handed melee attacks to ignore 10% of enemy armor. Source Bannerlordperks.
Throwing - Weak Spot 250
Throwing weapons ignore 30% of enemy's armor.
This perk correctly allows throwing weapons to ignore 30% of enemy armor.
In some older test with all perks I was throwing Javelins from standing that did over 1000 damage on head shots and then the perk Last Hit was not even activated for 50% more damage. Some peoples idea of Realistic Javelins compared to other weapons

Can Vandal stack with other skills, its says attacks but does not specify Two Handed Attacks or Melee Attacks or Ranged Attacks.
Two Handed - Vandal 225
Your attacks ignore 25% of enemy's armor. in game text
This perk correctly multiplies effective enemy armor by 0.75 (-25%) with all weapons. Source Bannerlordperks.
One Handed - Chink in the Armor 250
Your one handed melee attacks ignore 10% of enemy's armor. in game text
This perk correctly allows the hero's one handed melee attacks to ignore 10% of enemy armor. Source Bannerlordperks.
Throwing - Weak Spot 250
Throwing weapons ignore 30% of enemy's armor.
This perk correctly allows throwing weapons to ignore 30% of enemy armor.
In some older test with all perks I was throwing Javelins from standing that did over 1000 damage on head shots and then the perk Last Hit was not even activated for 50% more damage. Some peoples idea of Realistic Javelins compared to other weapons
