Spikes

Spicomellus had quite the dinosaur armor suit, but it never had to face spears or even swords; just teeth and claws and horns. Which admittedly are bad enough.

A youtuber asked if spiked armor (as in the fantasy pictures) was really ever used. Real examples are scarce (pickelhaube spikes were decorative and as of 1915 they were removed in combat to reduce visibility), and usually not obviously useful. Spiked shields could be handy, to snag your opponent's weapon briefly and safely away from you. Snagging your enemy's sword against your arm transfers a lot of momentum to your arm--much nicer to have it skid off smooth armor than catch, and maybe dent your armor and bruise your arm or worse. And fantasy armor spikes get in the way of moving smoothly too. And your friends might have objections.