There's a notable difference between a greek phalanx and a macedonain phalanx.
Greek phalanxes used shorter spears (the dory was ~2.3m long), larger shields (the aspis or hoplon (hence the name hoplite) is ~1m diameter) and a short sword (xiphos ~50cm long). While they started out wearing bronze cuirases (breastplates), they later moved to linothoraxes (made from linen glued in layers with animal fat, enhanced with some bronze scales, see the "example of spears" picture Perim posted).
Macedonian plalanxes used much longer spears (the sarassa is ~5m long), small shields (strapped to their arm, and no suitable for shield walls), a more chopping centric sword (kopis, ~50cm long). This was what Alexander the great used as the core of his armies. The longer spears (and combined arms tactics) was an advantage over the shorter spears of the greek phalanxes. These are also the phalanxes that were displaced by the roman legions, since such long spears are more unweildy outside of phalanx style warfare.
The sizes of the armies really isn't that unusual. Remember we're basically looking at bronze age armies in fights between small city states, not iron age armies and not empires from any ages.
Ferme might be talking out of his arse re: killing Almus, but I do think that killing/capturing Ferme would break the morale of his army. Almus is more of the figurehead, while the other guy is actually in charge (even though Almus and Co. are a huge power advantage).
@Perim
"- Lack of any serious armour. No mail. Not even gambeson." You've got to be kidding? They're using the most important armour you can get, shields and helmets. Except for the heroes, since
https://tvtropes.org/pmwiki/pmwiki.php/Main/HelmetsAreHardlyHeroic. It's hard to tell either way, but imo most of the troops look like they could be wearing some type of linen armour.
"-explodey spears". True, even a handful of stones packed around the gunpowder could have helped. I would have also tried to save them for when the formations were closer or engaged, to try and break the opponents formation.
"-formations! in/out/in/out!" I just chalked it up to Rule of Cool/Cinematic License or something. I do like that they didn't do the typical Hollywood nonsense of forming up in orderly, defensive formations, then throwing it all away by charging 100m at each and engaging in a stupid grand melee/skirmish.
"-wide open on page 15" True, but then he couldn't shield smash with great Son of the Griffon strength (he's the Son of the Griffon you know!) and throw mooks around like a dynasty warriors knock-off.
"-I'm engaged to Tetra" I initially thought that was mostly directed at Ferme, and that Ferme was aware of Tetra's lineage. I could be wrong though. Time between chapters, and too many isekai's and I tend to lose details of the storylines w/o re-reading the last dozen chapters.
I have no issue with the rectangular shields being used. I don't mind that much that Almus and co are the odd ones out using round shields, between "they're the heroes" and a not-uncommon rule that citizen soldiers provide their own equipment. My biggest issue is really that there was no skirmishers using slings, darts or javelins before the formations collided. Those large shields would stop most of it, but slings and stones are cheap, have good range and hit hard. Getting pelted is going to help unnerve the soldiers, and more than a few will get through to cause damage.
re: Bikini horse girl. Its a girl in a bikini on a horse, shut up and enjoy.