This comes dirrectly from my submission for CDC3.
Original Card:
Knight of Balance

Creature - Human Knight
If Knight of Balance has power equal to it's toughness then it has Protection from Red, Protection from Black, and First Strike.

: Knight of Balance gets +1/+0 until end of turn
1/2
So it pays homage to Black and Silver Knight, without being strictly better/worse than either.
The ability is intended to be static. So it statically toggles on and off in correlation with power and tougness. This does not use the stack (but obvisouly the pump ability does use the stack). This creates an Interesting drawback: You can't save him twice. For example, lets say cast shock on him. In response I activate his +1/0 in an attempt to make him Pro-Red. Now in response to the pump, you Lightning Bold him. Even if I have all the White mana in the world, I can't prevent both spells from landing (because if I activate the pump again in response he will Pro-Red the Lightning Bolt, but then be a 3/2 for the shock).
Rules Question:
How does a creature gaining and loosing first strike effect combat?
Lets put up a scenario: So I control the card above (as printed). I declare him as an attack and in that step I pump him to a 2/2 (which makes him Pro-Red-Black, First strike). Now blockers are declared and because he is Pro-Red-Black all your Goblins and Zombies are worthless. Now we move on to the First Strike Damage step. I assign 2 points of damage to you and when I get priority I pump him say.. 2 more times (makeing him a 4/2 who looses first strike). Now what happens when we enter the normal combat damage step? Do I get to assign 4 MORE damage to you (effectively giving him one-and-a-half strike?)
As a result of that rules question I offer the following resolution:
Current Wording
Knight of Equity

Creature - Human Knight
If Knight of Equity has power equal to it's toughness then it has Protection from Red, Protection from Black, and First Strike.
: Knight of Equity gets +1/+0 until end of turn, you can not use this ability while Knight of Equity is in combat.
1/2
That means you can still have him gain protection at any point durring your opponent's turn, even durring combat... so long as the Knight Himself is not in combat.