It's my first time here, sorry but are you larping?
>want to be able to [...] se guns or swords if neccesary,fight big opponents
I was about to ask if you practice HEMA or something but guns and swords? Fighthing big opponents? Where do fuck do you live mate?
Anyway, about your question: I mainly go for muay thai amateurs fights and I'm like 160cm@55kgs right now. I usually fight at 54.5 or 60kgs and I keep most of my strenght at 54.5 but I can't really beat someone that is heavier than me. At BJJ I can't do shit against someone who is like 4kgs heavier at 54.5 but at 60 I can at least survive against someone at 70kgs
>lifting the same as a big guy all the while being thin
I dont think that you can be lean and lift heavy without juicing but, hey, try it out.