"from what we know to this moment" Let's begin from how you get them. Rage are weapons can only be obtained trough events like Snowy Bounds; while arena weapon you obtain them from trading arena points in arena dealer.
And second the "rage" stat and "ferocity" stat. Rage is a temporary 10% dmg increase against everything (correct me if I wrong) , while ferocity is a continuos buff to damage dealt to players and a debuff to dmg dealt to mobs.
Marcos Veras got a reaction from Shuggar in [2016.04.26] Update Warspear Online 5.7: Temple of Seals. Preview