So, after a grueling several hours, I've managed to make a compilation of all of the icons that I've made over the years that are free for anyone to use. Since most of them are old (probably averaging from around 2008-2009, but there are ones that are even older on here), I'm not even going to care if people want to tweak them to their needs.
I'm going to link this solely as a Dropbox link as, should I make something else that's free to use, I will simply update the file and append in an edit to this post (unless it locks you out after a certain length of time) noting what's been added. (I also very rarely do stuff with my Dropbox, so the link should always be valid.)
(Background color legend:
Green = adaptation of existing FE weapons/icons (mostly FE9/10 stuff)
Yellow = icons made for Arch for Elibean Nights (that are completely new and not versions of things like the Rusty Coin) that he has allowed to be free to use
Blue = icons that I've done over the years either for myself or defunct projects (some of which may have been appropriated by Arch or other projects since)
I'll also tease that I have an enormous project that I'm ever so slowly chipping away at that is going to be an entire package of free-to-use icons. I'm just not nearly close enough to show it yet.
EDIT (5/23/15) - I've updated the sheet with a new icon that I forgot when initially compiling the sheet, my take on FE6's Eckesachs.
EDIT (3/29/17) - Link updated to due Dropbox being dumb.
EDIT (Jul 7, 2017) - Ditto the previous update. >:o
Also, at some point I did a new version of the Bolt Axe and added that to the sheet as well.
EDIT (Nov 25, 2017) - Remembered a few old icons that I hadn't included on the sheet as well as a new version of the Cleave Bow for EN since the old one was absolutely ancient.