I'm having some difficulty at understanding the combat rules for hitting a helpless target and how it may proc righteous fury, in the rules it says:

1) hitting a helpless target always succeeds

2) when hitting a helpless target you roll damage twice:

If one damage roll is 10 Righteous fury might happen as normal and if you get a second 10 it then makes the righteous fury automatic. (Of course against filthy xenos marines don't need to roll anyways because of the training they get)

My problem is as follows: Because hitting a helpless target always succeeds anyway wouldn't the righteous fury happen automatically even if you didn't roll the second 10, since the righteous fury confirmation roll to hit always happens with the same bonuses that applied to the initial roll? So what is the point of the text concerning the second 10 "confirming" the already automatic righteous fury?

Of course this isn't that important gamewise since if my marines meet and decide to hit a helpless target I'm more than happy to just give a very gruesome description about what happens to the poor fellow/heretic/filthy xenos , but this rule has still given rise to some interesting banter in our group and so I decided to post it here.

Alrighty, when hitting a helpless target you do roll damage twice. A target that can't even move makes it pretty easy to slit its throat.

Now if you score righteous fury on one of those damage rolls you, of course, get righteous fury. Even though the original attack automatically hits, you still have to roll your WS with modifiers to confirm the righteous fury. I know what you are asking, "If the attack automatically hits wouldn't the righteous fury automatically confirm?," but no, it still requires the confirmation. In this case only the initial attack is automatic. But lets be honest if the target is helpless you've got some pretty good bonuses to hit there. If its a xenos, well don't worry about it you've auto furied.

If you happen to score rightrous fury on both of the damage rolls your righteous fury is automatically confirmed. No rolling to confirm. If this happens on a xenos, too bad so sad, nothing extra happens. These rules are the same a normal non-deathwatch trained character has. Your special auto-confirm vs. xenos doesn't give you anything in this cenario. But lets be honest auto-confirming against xenos is pretty buff in its own right.

Now, in order to get the auto-confirm (without xenos) with this effect you must righteous fury on BOTH damage rolls. An attack with a 2D10+ weapon will not auto-confirm in this instance if you roll 20 damage (two 10s) on a single damage roll. You must roll at least one 10 on each damage roll.