have you tried thrusting with a spear holding it overhead? your wrist movement is severely more restricted trying to keep the spear going straight instead of downwards. i also don't get where you get the idea from that you can't stab with a spear from underneath the shields whilst they're overlapping.

You cannot use underarm spear thrusts with overlapping shields I don't understand why you would think they didn't use overhead thrusts, which is easier on the wrists too.

nice!

@Priyon | प्रियॉन Unlikely. In "Christopher Matthew's A Storm of Spears: Understanding the Greek Hoplite At War (2012)" he seems to think the underhand thrust was used a lot more commonly, and generated more power, reach and precision. There are a fair number of depictions showing an overhand grip but there are also a few showing the underarm grip too. He argues that these grips coincide with depictions of javelins vs spears, as often the weapon in use is gripped 2/3 down the spear when used overhand but half way of the way down the spear when used underarm.

why do they hold their spears over armed

yes, the eternal discussion haha

Well yes, even at that time, they did not fight like the Macedonians but like the Greeks.