I'm very unskilled so in fallout 4 Swan fucked me over pretty hard on my first playthrough.
But I can replay this kind of game dozens of times... on my second playthrough I was prepared.
I had several good guns, lots of ammo for all of them. I had learned how the favourites worked, and all of my good guns had been in the same slots in my favorites for hours, so I knew how to switch from one gun to the other.
I was familiar with which favourites slot my stimpaks were in.
I had a strategy: I was going to throw frag grenades into the pond, so he would already take some damage before he even broke the surface. I had a plan to take cover behind an old military vehicle, and if he got close I could run inside it, he wouldn't be able to follow me in there but I would still be able to shoot him.
So I threw my frag grenade... but it wasn't a frag grenade, it was a Minutemen artillery smoke signal grenade. Artillery absolutely rained down on the whole Boston common for a long time. He was absolutely wasted. All I had to do was watch...