User blog comment:Mckrongs/Monster Hunter 4 for the Nintendo 3DS/@comment-83.165.23.90-20121214224500/@comment-115.135.246.211-20121216081311

I think I read somewhere that you can only charge that phial while in sword mode and only use them in axe mode, so you need to use both form to make full use of the charge. Or I could be wrong though :P