I agree completely with Ladof, but want to make his first sentence disclaimer a little clearer.
1. when the 3/3 soldier token (vanilla 3/3, no first strike or double-strike) attacks, you declare
Fabled Hero as the blocker.
2. you cast
Test of Faith, targeting
Fabled Hero.
3.
Fabled hero Heroic triggers, as does
Hardened Scales, making it a 4/4 double strike.
4. First strike damage is dealt and the 3/3 token dies
5.
Test of Faith never goes off since
Fabled Hero receives no damage.
Now, if you wanted to get the maximum (realisitic) benefit out of
Test of Faith, you can let the first-strike damage occur, then cast
Test of Faith so that
Fabled hero gets all the counters as Ladof describes.
And to answer your original questions, in the case of combat,
Hardened scales would only give 1 additional counter since all the damage is dealt at once. In theory you could get the full 6 +1/+1 counters if the damage was dealt individually (as described below).
Let's pretend instead of a 3/3 soldier, you're facing a 1/6 double strike creature (not even sure this exists but just go with it). It attacks, you block with
Fabled Hero and Cast
Test of Faith, like before, it becomes a 4/4 double strike.
Now first strike damage happens, and
Test of Faith prevents 1, giving you 2 +1/+1 counters thanks to
Hardened Scales.
Before regular damage, you tap your
Goblin Sharpshooter (sweet deck man
) and deal 1 damage to
Fabled Hero, giving him 2 +1/+1 counters.
Then regular damage is dealt, and another 2 counters are added to
Fabled Hero, making him a 10/10 double strike and capable of swinging for lethal on crack-back.
Hope that clears things up
Good Luck!