If they have no shield then they would be using the spear two handed which would change the damage dice to 1d8? I guess with the guard captain and tough boss having multiple damage dice for a single hit and no ability explanation of that they're changing NPC stats from being exact representations of equipment and player abilities on NPC stats to a more almost monster like stat block. Like how NPC duergar enlarge and double damage dice while player duergar just get enlarge/reduce which makes the extra damage only 1d4. Is simple and makes sense. I like the new design method and space but wish the standard soldier felt a little more. Pack tactics does make sense though for warriors

I am quite sure that this NPC is the renamed Tribal Warrior.

This stat block also does not match the art and description. It is absurd that the gears and attributes of these trainees are even worse than those of the Guards, who have little martial training. According to the lore,  as the rank-and-file troop, Warrior infantry should be significantly stronger than guards, and their CR should be around 1/2 to be more appropriate.

I agree I feel like this should be the soldier stat block from Guildmasters’ Guide to Ravnica, as that feels more like infantry to me. 18 AC, 16 hit points, with a mulitattack it often what I use for the troops better trained then guards but not higher ranked.

why are war infantry weaker than town guards?

I see the rest of you generally suffer the same annoyances I have. Im one who prefers for gear and abilities to match stats and load out. While it adds granularity to allow monsters to have special attacks with adjusted damage, etc, I would still love it if they had a mechanical ready for it. Perhaps guard captains, who get to do more damage than their stats and gear would suggest, should have a trait called "Brutish" or something. Anything to help my brain reconcile the differences.

Make them CR 1/2 by doubling their HP, giving them a shield and adding Multiattack (2 melee attacks). These are just puny otherwise.