Some more idea which probably don't work, but would be nice:
Normal Arrowheads do NOT combine with arrow shafts (because of free infinite normal arrows)
Normal Arrowhead + Fire Scroll = Fire Arrowhead
Normal Arrowhead + Air Scroll = Stunning Arrowhead
Normal Arrowhead + Water Scroll = Chilling Arrowhead (inflicts Chilled status)
Normal Arrowhead + Earth Scroll = Poison Arrowhead
Normal Arrowhead + Witchcraft Scroll = Debuff Arrowhead
Normal Arrowhead + Water Flask = Water Arrowhead
Normal Arrowhead + Oil Flask = Slowdown Arrowhead?
Normal Arrowhead + Poison Flask = Poison Arrowhead
Chilling Arrowhead + Chilling Arrowhead = Freezing Arrowhead
Fire Arrowhead + Flask of Poison = Explosive Arrowhead.
Fire Arrowhead + Flask of Oil = Smokecloud Arrowhead.
Fire Arrowhead + Flask of Water = Steamcloud arrowhead.
Stunning Arrowhead + Flask of Water = Static Cloud arrowhead
Stunning Arrowhead + Flask of Poison = Poison Cloud arrowhead
Stunning Arrowhead + Flask of Oil = Smokecloud Arrowhead?
Of course, you would need to be able to make flasks of oil and water, which you can't right now.
