Dumb ideas

The Beast of Swords

World: Fate(Nasuverse)

In this world instead of Sengo Muramasa being a human blacksmith he was an actual Demon and a True Daemon (demons and daemons are not the same in fate, demons are your normal demons like imps and stuff, daemons are eldritch horrors that were born from human concepts but the concepts became so twisted that they are eldritch and incomprehensible to humans, at least that how I understand it the wiki wasn't that clear) and because of this little change Shirou isn't a normal human, instead he is a mixed blood. This leads to him being very different in terms of his personality and his powers. 

Here Shirou would be a jerk with a heart of gold.  Mean of the outside, but nice on the inside. He cares a lot about people and can be very perceptive when he wants but in the end he is still the lovable, distorted, borderline suicidal idiot we all know.

He has Muramasa's ability to see karma, the quantity and quality of his magic circuits are far higher due to his inhuman heritage and he also haste a variety of fire and weapon related powers. The reason he has fire powers? Well the way I understand things daemons are born from human ideas and concepts that have been twisted into an incomprehensible form. So in this story the concept that Sengo was created from was "the duality embodied by fire" what do I mean by duality?  Fire can be seen as a symbol of progress, as the discovery of how to use it was vital to humans, but it is also a symbol of calamity and ruin for obvious reasons. This is why Shirou has fire powers. He can absorb fire to replenish his energy in a way that's similar to the galvanization skill possessed by Seig and Fran. He can also summon 2 kinds of magic fire. The first one has is corrosive and can even destroy things like souls and magic circuits, it has the same properties as the cursed fires from the Fyuki Fire but slight watered down, this is because his previously ability meant his body began to absorb some of the cursed fires so when Kiritsugu put Avalon in him it integrated the cursed fires into him. The 2nd type has the power to restore and enhance things, it has the same properties as Avalon, he can use it because of Avalon being in his body for a long time causing him to gain some of its abilities, if he is injured the area around the wound will heat up and start to smoke a bit if it's a small injury or the fires will cover the wounded area if it's more severe. He is also far more in tune with the world around him due to Avalon being a Faerie relic, this means his instincts are very good letting him sense and react to danger prematurely(basically spider sense), and he can sense things like the emotions of others, wether or not they are lying, the flow of energy, souls, all those metaphysical or spiritual type things. He is also capable of tracing things he normally couldn't(like guns) largely because of the esoteric and eldritch nature of daemons, allowing him to comprehend more complex things, he can also design new weapons, however any new weapon he makes must be something that can be produced using materials, methods, and magic that he has previously analyzed, this particular ability is important be cure it ties into his next power. This next powers are going to be the obligatory "cheat powers" we fanfic lovers are so obsessed with. What is it you ask? His last power is the Authority Of The Beast. Yup Shirou is one of the evils of humanity here.  All Beasts are related to an aspect of humanity's innate bestial nature,  Shirou is the beast of subjugation, he embodies humanity's nature as apex predators, beings who destroy all things in their way and conquer everything around them even the world and other humans. They are masters of killing who are always getting better. All beasts authorities behave a bit differently from each other, Shirou beast authority has three parts, the 1st represents how humanity is always improving its knowledge it let's him analyze his oppositions abilities, strengths, and weaknesses seeing how well suited he is to fighting his opponent, the 2nd part allows him to draw energy from the world around him to strengthen himself to the point where he can simple overpower his opposition, the 3rd is a form of self modification and makes use of his ability to make swords, Shirou can trace weapons inside his own body(like what HF Shirou did but more controlled) and can integrate the properties and abilities of the weapons into himself when used in conjunction with the 1st part of his authority it lets him analyze his opponents weakness and advantages and then lets him adapt to better exploit the weaknesses and nullify their advantages, effectively letting him adapt to any situation. It should be noted that all 3 parts of his authority can be used outside of combat, allowing him to overcome any obstacle. He also has a sort of Beast form, where he just turns into a sentient mass of fire and weaponry, he can change this forms shape and appearance due to his authority but aside from making difficult to injure due to being a mass of fire and metal, and letting him use the 3rd part of his authority with more ease it's mostly just to look cool.