I am playing on Thornblade, in the Secrets of Faydwer expansion, and I just noticed while looking at my next rank of Companions Fortification (Rank 12) that it appears to do nothing, but costs 5 AA points. Going from Rank 10 to Rank 11 moves from Fortify Companion I to Fortify Companion II, which bless the pet with Companion's Fortification II Going from Rank 11 to Rank 12 moves from Fortify Companion II to Fortify Companion III, but the description notes that this tier also only blesses the pet with Companion's Fortification II, and there are no passive increases to pet health or avoidance. The rank apparently improves nothing compared to Rank 11. Szilent on the beastlord discord looked up the spell IDs: 49815 (Fortify Companion II) and 49816 (Fortify Companion III) and noted that they both trigger cast spell 12777 (Companion's Fortification II).
