I don't believe there has been an actual topic made for this, at least my search didn't find one, so if this has already been reported than I apologize for the double post.
I was playing around with my pet and using #mystats to check the stats of my pet as I was giving him items, and I've found that the haste mask, and any other non visible item (like the summoned focus jewelry, or the belt) is not giving the pets the stats which tells me that the pet isn't equipping the items. I tested each individual item, looking for ac, stat, or hp increase and only the summoned chain armor (only visible slot items I can summon atm) gave my pet the appropriate increase.
So far the only items I've found the pet to actually equip are weapons, and any visible slot item. If this is not on your list already of things to fix for pet classes, would you please add it Chaos, or whoever would take care of this bug?
Thanks!
Insedeel