thank you for the tips and i am still considering letting the shield and armor focus feats be stackable or scale.
Well, they
need to scale, otherwise they will become less and less useful over time. Remember: a static bonus to a roll that checks success works differently than a static bonus to
damage. Here are some numbers:
Lets say at level 2, you do an average of 10 damage per attack, and at level 10, you do an average of 50 damage per attack. Now, if you have a 50% chance to hit, then at level 2, your average
expected damage per attack is 5 (50% of 10), and your average expected damage at level 10 is 25. This makes sense.
Now, if you add a +2 boost to hit (affecting the
success of the attack), this translates into a 10% boost to your success. Now, the level 2 guys has an average expected damage of 6 damage per attack (60% of 10) and the level 10 guys has an average expected damage of 30 per attack. Note how one guy increased his damage by one point and the other by five from the same +2 bonus to the attack roll.
Now, if instead, you were to apply that +2 to
damage, one guy is getting a 20% boost to his damage (10 to 12) and the other is getting a paltry 4% boost (50 to 52). That's five times the difference. So, any static modifier to damage
needs to scale with level or it
will fall into obscurity. Not scaling it only works in systems where you don't deal extra damage as you gain levels.