It unlocks all of the weapons, signature weapons and skills right from the beginning so you can purchase these any way you like and do not have to do 'X amount of missions to unlock this' etc. The Open World mod is for people that want to play the default game (no changes to weapon damage, crafting, etc.), but want everything open from the very beginning.
I'm excited to let you guys know about a Far Cry 4 mod I created that you might enjoy - the Open World Mod. ' class='fancybox' title='' data-fancybox='topic" data-type="undefined" target="_blank"> ' alt='' />