Here are three metal concepts for the game 
Chr_liq is chrome liquid, like liquid metal or mercury in appearance, yet it has an ability for absorbing technology. If the synth-fighter has the tech level for absorbed tech, it may transform and use it.
Seg_gold is segmented gold, one of the stronger metal composites in the game, it may undergo tremendous heat-strain.
Alloy_gr is alloy green, a composite metal material that takes on the base qualities of the energy that powers it's wearer.
Update:
Here I am thinking of different factions that all are types of coders / developers. Like groups that compete / teams of coders with each team having an expression to make through the synthetic warrior they create or something
Update:
I was also thinking that if certain metals react to energy sources such as alloy_green mentioned earlier, those energy sources could be soul-energies or captured essences or something like that.
So, for instance:
Let's say there is a clan or group of coders / fighter developers that are into spirit magic, and they have spiritual essence of let's say a type of Oni / demon available.
What would then happen, through coding (character creating the synthetic fighter) and releasing the spirit essence as energy source into the synthetic body of the fighter, the spirit essence would manifest visually in the synthetic body as having a similar look to that of the Oni / demon.
