I looked through the source to see if it was just removed in my pack, or via a method I wasn't seeing (drop an iron hammer in a mana pool I thought?), but didn't see anything. In your recipies file...

https://github.com/MikeLydeamore/Ex-Astris/blob/master/src/main/java/ExAstris/ExAstrisRecipe.java

...there are recipies for everything else, but not for the Manasteel hammer. This can be fixed in a pack via modtweaker or the like, but it seems there should be at least a recipe in the mod.