Lionheart is a GR9 longsword which can only be acquired through binding the Evils bane+5 and a fire dragon heart. it has an ATK of 124 and is only available to be equipped at lvl 46+. this sword is also used to bind 2 other swords - Red Wolf and Devilbringer.
to aquire the Red Wolf, you need to upgrade the Lionheart to Lionheart+5 and combine this with a fire dragon heart. to upgrade the Lionheart to +5 you will need: 5x lvl 7 chromium pearls, 14x black iron ores, 2x Demon fossils and 1x destroyer fang. the destroyer fang can be aquired by defeating the pyredaemus rex which can be found in the Station Attendant quest. Chromium Pearl Lv. 7 can be obtained through completing GR9 quests and black iron ores and the demon fossils can both be harvested in GR9 quests or in georama towns.
To acquire the Devilbringer you need to upgrade the Lionheart to Lionheart+9 and combine this with an Earthbeast tail+. to upgrade the Lionheart to +9 you will need: (the above to get to +5) as well as: 4x lvl 8 chromium pearls, 5x black iron ores, 8x Demon fossils, 7x Destroyer fangs and 2x Fire dragon horns. the only new item in the list that isn't required to bind the redwolf is the Fire dragon horns. these can be acquired by defeating the fire dragon in the KoDII quest. Also, they can be dropped by the dragon when attacking it's tail.