I'm actually loosely familiar with the armor you are talking about (if it's homebrew, there is an actual RAW version, just so you know). I don't recall the name off the top of my head (that said, I'll probably find it in the next few days anyway).

Anyhow, to the point of the matter -- if this is the armor I think it is (and I only know one that does this), then RAW I believe it does state he is immune to his own armor's ability.

Allies, however, are not covered in that statement.

Please note that I'll probably be nagged by this question, so this answer will likely be edited once I find the reference.

I'm actually loosely familiar with the armor you are talking about (if it's homebrew, there is an actual RAW version, just so you know). I don't recall the name off the top of my head (that said, I'll probably find it in the next few days anyway).

Anyhow, to the point of the matter -- if this is the armor I think it is (and I only know one that does this), then RAW I believe it does state he is immune to his own armor's ability.

Allies, however, are not covered in that statement.

Please note that I'll probably be nagged by this question, so this answer will likely be edited once I find the reference.

EDIT: Yep. Found the armor -- it's called Mithralmist Armor. Tenative citation is MIC, but I'll have to dig further to check this.