The upcoming Fire Emblem If will be introducing a few new changes to the established formula, along with a new difficulty setting to further ease the burden of losing units in battle.
According to Famitsu (via Siliconera), weapon durability will be removed completely, thus eliminating issues in previous games where players had to save their best equipment and spells by wasting inventory slots on other options.
Fire Emblem If will also add a new Phoenix Mode that further builds off of Casual Mode (which also makes its return). While the latter removes permanent death of units after a map is completed, the former revives any fallen units after every turn. It will be interesting to see how this works, especially if the player opts for the more difficult Nohr path.
It also seems that a new ability called Dragon Pulse will be added for some characters which can alter the foundation of a level entirely through earthquakes or crushing mountains.
Fire Emblem If is out on June 25th for the Nintendo 3DS in Japan. It will be out in 2016 for the West.