What is the meaning of Free Mode and Story Mode in True Three Kingdoms Undisputed 5!

Story Mode, also known as Undisputed Mode, is a mode that tells the story of each Undisputed General, and each Undisputed General's Story Mode consists of six levels, in increasing order of difficulty. The story of each of these generals in Story Mode is different from the official history of the Three Kingdoms. Free Mode allows you to play any of the levels in Story Mode with any of the generals you choose (including non-Superior Generals). Some levels in Free Mode need to be unlocked by playing Story Mode. I've seen some people say that the story mode can brush good weapons, this is very wrong, free mode is the best place to brush good weapons and good army horses, otherwise the non-double generals do not have the corresponding story mode, so how can they brush weapons?