Background:
Lunge cannot be used to gain any benefit in any situation as currently worded.

1. Every attack, whether guarding or normal, must first declare the space to be attacked. This is the very first thing in the attack sequence.
2. If it is a melee attack, it can only be declared against an adjacent space (unless you have Reach before you declare the attack).
3. The wording of lunge says play before the dice are rolled when making a melee attack. In order to be making a melee attack you have to have declared the attack already.
- the sequence is (must be) declare attack, play lunge, roll dice.
But then Lunge doesn't work, because you must have already declared the attack (without Reach, so against an adjacent space) before you play lunge.

Therefore, the only logical explanation is that Lunge can be played at the same time as you declare the attack, allowing you to resolve Lunge first, gain Reach, then declare the attack is targeting a non-adjacent space.
Suggested Errata:
On the Feat card Lunge, replace the text with;
Play when declaring a melee attack.
You gain the Reach ability for that attack and may declare a non-adjacent space as the target space of the attack.

Commentary: This would allow the card to be played before declaring the target space and thus allow non-adjacent spaces to be targeted.
It would also work for Guard attacks.
A question may then arise as to whether Lunge can be used with the Counterattack skill from SoB.
After an enemy figure in your melee range rolls a miss result you may immediately make 1 Melee attack against that figure. You may do this once each time an enemy figure in your melee range rolls a miss result.
I personally would say that no, you cannot combine the two as the Counterattack allows you to make a melee attack when the enemy is already inside your (normal ) range, while the Lunge card extends your range only after/when you can (already) declare an attack (with either original or proposed wording). But others want official word…

Possible Question:
Q. Can a lunge feat card combine with the counterattack skill to counterattack using the Reach from lunge at a non-adjacent figure?
A1. No. You have to be able to use the Counterattack and ‘get’ an attack before you can play the Lunge card, and at that time the figure will not be within your melee range so you can’t use Counterattack skill.
A2. Yes. Counterattack and Lunge can be combined to allow a hero to counterattack another figure that is 2 spaces away.