Ok, so I am sure we all played the Space Marine Demo by now. I love how you gain health.
So I was thinking about using the following dynamic to adapt that idea into Deathwatch
Solo Ability: Wrath of the Emperor's Chosen
Minimum Rank:1
When an enemy is reduced to zero or less health, the player may opt to invoke this power. The enemy must be a significant challenge to the character (up to GM). Doing so is a full action, and the player rolls to hit with Weapon Skill at -20. As long as one point of damage is done, the enemy is killed. Also, the player must suitably describe how his character is impressively ending his enemy's life. Doing so causes the character to regain a fate point. This may be done once per combat.