Ok, here's the RAW breakdown...
Codex: SM said:
If a Space Marine Commander is on the table then all other Space Marine squads may use his Leadership for Morale, Pinning or Leadership tests, but not Psychic tests.
And from the more recent Codex: Blood Angels
Codex: Blood Angels said:
Rites of Battle: All other Blood Angel models in the same army may use this model's Leadership for Morale, Pinning and Leadership tests but not Psychic tests.
Emphasis mine in both cases.
There's some subtle things to note.
Codex: SM Rites of Battle affect *only* SQUADS
So individual models singled out to make Morale, Pinning or Leadership tests do not benefit. Period. (It says squads, not Units, not Models) This is same situation as having a Vet or IC attached to the squad with a higher LD score. The score is used for tests the Squad makes, but not for individual models.
However, the new DA/BA version does say Models, so you can be singled out and still use your commander's LD score. So let's continue the discussion under the assumption that we're playing with one of the New SM Codices.
But note that I highlighted 'Leadership tests'.
Leadership Tests are defined on p12 of the BBB as being 2d6 addeed together and compared to the model's Leadership score. A Leadership test is a very specific rule, and RoB very specifically benefits *only* Pinning, Morale and Leadership tests.
Now, for Mind War...
Mind War 4th ed Eldar Codex said:
The Eldar player may choose any unengaged model within 18" of the Farseer and within his line of sight (models in vehicles cannot be targeted). Both players doll a d6 and add the Leadership of their respective models. For each point the Farseer wins by, the target loses a wound, with no armour save allowed.
That is NOT a Leadership test. That is an opposed d6+Ld roll. It is never called a Leadership test, it does not use the mechanics of a Leadership test. Nor does it use the rules for Morale or Pinning.
So, even if you're playing a New SM army (as we've already established old Codex SM armies cannot use RoB on individual models), it still makes no difference, as RoB very specifically only benefits Pinning, Morale and Leadership tests, and Mind War does not invoke any such test.
So you're pretty much SoL if the Eldar player wants to melt the brain of your guy with the Lascannon