Missable!
For this trophy, you must collect 15 Phoenix Feathers to fully upgrade your magic to maximum. There are plenty of opportunities to collect these for there are more than 15 Phoenix Feathers in the game. Once you've collected the 15th Phoenix Feathers, this trophy will be yours. All other Phoenix Feathers chests found later in the game will turn into red orbs chest with either green/blue orbs.
This is PowerPYX's guide. All credit goes to his fantastic work. He list all 45 colelctible's unlike playstationtrophies which only site first 15 of each.
http://www.powerpyx.com/guides/god_of_war_ghost_of_sparta.ht...