Ok, so after some playtesting our roleplaying group decided that the flame weapons rules are unplayable- many characters simply burn to death (since they suffer a level of fatigue every turn) just because they got hit by flamers and they don't have much WP and/or Agi, and against- for example- orks a single flamer can effectively disable and eventually burn to death a few hundred enemies. Here's what we came up with (funnily enough, it's actually simplier than original rules).
All flame weapons gain +4 Damage and +2 Penetration, to make up for the changed setting ablaze rules.
Firing with flamers
1. Declare targeted zone; check how many targets will be affected
2. Roll a d10: on a roll of a 1, it jams.
3. Every affected character rolls agility (+0). If it fails the test, it is damaged by the flamer. If it fails by three or more degrees of failure, it is also set ablaze.
4. Resolve damage (we decided to roll separate dice for every affected character, but it's mostly personal preference)
Ablaze characters
Any character that is ablaze takes 1d10 damage ignoring armour, but not toughness bonus. If the character takes damage (if it wasn't reduced to 0 by toughness bonus), he also suffers a level of fatigue (this effect can cause a maximum of 2 fatigue levels).
Next (even if no damage is caused by the fire), the character rolls Willpower (+0), affected by all talents, traits and special rules that would affect fear(2) (other than insanity of 40 or more). If he fails, he immediately drops to the ground, and it cannot make any actions. Instead, it's trying to put out the fire- Agility (-10).
If the character succeeds in the willpower test, he can act normally- in addition, it can try to more thoughtfully put out the fire- half action, agility (+10). If the character is trying to put out second time, the second attempt is an agility (+0).
If a character is wearing a void-sealed (or similarly secured against vaccuum) armor, he cannot be set ablaze by weapons with AP weaker than that of the armor (for example, a Flamer cannot set a character in Power Armor ablaze- but it could do so with a character in a void suit)
Edited by Elavion