I built 6 Resodan Danelectro Conversions between 2007 - 2014 & the one played by Hozier looks to be one of those guitars.
I've just come across the now New model from Danelectro so its quite nice to see their input into the resonator conversion too.
Original conversions were done by Holiday Music so i cant take any credit for the first conversions but having read up on the original conversions in Guitarist magazine a very long time ago i decided to do the same. See the link below. http://www.julianmullenguitars.co.uk/Resodan.htm