ok but i was also thinking about shinji &&. alchemy 

so u know how like… everyone in FMA seems to have some sort of alchemic– wait no its just roy but i mean ok I bet Shinji would figure out some sort of specialized alchemy, too, as an extra thing to the generics. Note, the Eizenbern family knows alchemy, although their specialty is obviously HOMUNCULI. Likely, most alchemists in the Nasuverse would be able to develop their own unique styles, or have a family style handed down. 

Anyway, as to what Shinji does–

Honestly, part of the reason he went to alchemy is because yeah, his magic circuits are fried until the remnants of whatever halfassed grail are still in his body decide to release energy. Literally the energy release functions so that his body doesn’t break. It hurts like fuck but that’s why he’s not a horrid mess of whatever grailstuff. Considering that as he grows older he also becomes more aware of the fact that i mean…. where else could Iliya’s heart have gone I mean… 

So knowing that he’s at least a halfassed grail, Shinji decides to put that to use, much as someone would put a philosopher’s stone to use. While he’s unable to bypass the basics of equivalent exchange, he usually channels completely off of his own energy, as energy is still a thing that can be at least slightly converted. This is his main ‘defense’ or ‘attack’, because like magecraft, alchemy can be used as a weapon. Since it’s energy conversion, he can’t make any solid things from it, but … 

it’s still pretty damn cool. For any normal non-weird energy conversion transmutations aka transmutation of existing matter, he has to use alchemy arrays/transmutation circles etc. Since the grail powers the energy to other energy conversion, he needs no symbols or circles for that. 

His use of grail energy for essentially metaphysical attacks is designed specifically to deal with familiars &&. summoned shit. Why? Because he left to study alchemy not only to prove he could do shit, but to find a way to rid his sister of Zouken’s worms. While worm-familiars are said to be the lowest of familiars, it’s pretty clear that Zouken’s worms are like supercharged &&. for that matter &&. since the crest worms in Sakura’s body are also infused with shards of the fourth grail ( Shinji &&. Sakura are the remnants of the fifth &&. fourth grail, respectively ), he figured that only a non-physical grail fueled style of alchemy would be able to exterminate the worms without damaging her body any further. 

Depending on what he’s up against, he can use what’s essentially lightning &&. yes, he’ll fight a servant with it if he has to. Over time, he’s realized that the Grail will do anything it can to cling to his body as a host, thus it often kicks in &&. does the energy thing when he’s in danger of …well… death. No, he can’t go up against top-ranked heroic spirits &&. escape unscathed. Yes, Gilgamesh will kill him, but also yes, the style of alchemy that he prides himself on is designed to do damage mainly to spirits. A familiar is also a spirit fun fact just in case. 

If he ever finds students &&. or somehow manages to have a happy life &&. have kids etc, he’s going to do whatever he can to pass on the new ‘Matou alchemy’, because hell, it’s cooler than the Matou magecraft.