Why was plate armor invented? I've read two separate texts on to why, one of them said it was designed to better protect against bladed weapons like spears and axes, which led to the creation of anti-armor weapons like maces, and the other said that plate armor was to protect against musket fire, in other words, did plate armor come before or after black powder weapons?
did plate armor come before or after black powder weapons?
Before. Early plate armour developed over the 13th century, while early firearms developed over the 14th.
But when gunpowder weapons did arrive on the battlefield, armour had to adapt. You can read about the relationship between early gunpowder weapons and plate armour in this answer by u/WARitter.