I am the definition of a casual player when it comes to Fire Emblem Heroes. I have been logging in since it came out, so I have many 5 star heroes at level 40. I mainly just like to collect the characters.
That being said, once I get them all to level 40, other than merging them with other level 40 heroes of the same person, how can I improve them? I have used the SP on them all to buy the skill upgrades... but that's it. Should I be trying to fill their skills by making manuals out of people so they don't have any blanks? What do I do with Heroic Grails? Is there something I can do with items? I don't think I've ever used any items or accessories or anything.
I know I'm a strange case, but I feel like I have a bunch of stuff and I don't know what to do with it after having my people all hit level 40. I tried to find a "how to play" guide that explained but couldn't find anything.