I think Sej should not be on that list; her AAs are not where her damage come from, so It just don't make sense for her.
I used to use this on Pantheon a lot. I found the mana regen on an AD item where excellent for letting me stay in lane forever. I found it also helped farm a lane quickly. I stopped using it when I was lower level and someone made fun of me for using it. (DONT LET SOMEONE DO THIS TO YOU! :*[ )
As others have said, the splash range is WAY too small. For instance, if you have 3 minions "shoulder to shoulder", and you attack one of the end ones, the one on the other end will be outside the range. I tried throwing this on Malphite at one point to synergize with his W. However, I found malph's splash range was good, but the tiamat's was not.
A way I would recommend this being fixed is to increase the range on the splash. However, a 200 splash radius might be too large for ranged characters, but Kayle's 150 radius might be good. So, make the splash radius larger, but I feel you can make it even larger for melee characters. 150 splash range for ranged, 200 for melee.