yes yes i do. It is in this cavern (with lava) but there is a downside to the sword of mana.
W a r n i n g S p o i l e r B el o w
In the cavern you get the sword of mana after defeating the boss (that looks like a snake I believe) however the sword is rusted and useless. So to spill the beans, there is no magical sword of mana, it was a symbol of heroism back in the day when it was used. So sorry, you never get to use it as a weopon but I hope I have helped answering your question.