TheGenerator says:
Got a hit, but pretty low damage. That might not be the final blow
On a 10+ you could choose to take a hit in return for another strike, or choose to remain safe.
Above average damage numbers will end this. If you are heroic in your conquest --and sufficiently credit Raynor with it-- you may even find yourself toughened by Raynor's blessings (gain the Tough Special Ability) for a while.
Below average damage will not 'kill' it and would not count as 'conquest', so there is a risk of death on this choice.
Or...
Deoring can steal your kill and have to come with his own one-liner.