As DanKensington pointed in a previous question about medieval battles, you can have a good idea of what they actually looked like here :

• u/Iphikrates and u/Rittermeister note how it went for the Greeks and the Medievals;
• Iphikrates also goes further into the 'pulse theory' of combat;
• so does u/Hergrim (with a bit more Iphikrates) in this post asking about rioters versus police.
• and more Hergrim on the dimensions of combat.

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As for your specific question, individual skills of soldiers tended not to matter that much. For reason highlighted above : victory is above all a question of formations, holding the line and keeping your nerves, rather than slashing everything you come accross.