So during a game, the guy I was playing against claimed i'd lose my armour piercing on my glade riders after the first turn of combat. I was confused, as the weapon clearly listed them as being armour piercing.
Then I read the rulebook and it states that a mounted model with a spear, may only use it's spear on the turn it charges. In subsequent turns or if it did not charge, it uses it's hand weapon instead.
Lo' and behold, the glade riders are also armed with hand weapons, so I lost my armour piercing.
I had no idea this was the case, I feel kinda dumb for not knowing the BRB spear rules.