fearsomepirate
Hero
Pedantically: if you had PAM and Dual-Wielder, and were using two spears or quarterstaffs, you could trigger both, which in this case is two extra spear attacks.
"Only a...spear" means one spear. You tell your son, "If you eat only a cookie, you can have ice cream, too." He eats two cookies, one with each hand. Does he get ice cream?
I'm not saying that's a problem, because only Vhumans can get there without letting their ability scores fall behind, and for non-vhumans it's a later-stage benefit anyways. In other words, it allows for a crazy combo, but frankly I find those more fun than broken.
Edit: and this combo doesn't get the soft twf benefit of being dex-based.
Yeah, I ran numbers, and even with such a generous reading, it's a ~20% damage increase in exchange for a fairly significant hit to defenses & HP. Not at all out of line with what two feats gets you. Be strict about PAM, and it's a ~10% increase, not even worth it.
I find it interesting how hard it is to find something really broken. I'm sure there's some really asinine MC glass-cannon combo involving a bardlock bladesinger or something.