Never actually had anything taken off me, nor had any serious damage from a fight besides bruises and a sore jaw.
One time this bunch of dickheads were causing trouble on the train, asked for my phone and wallet then started slapping me around the head. I walked [slowly] away and when they started following me, other people got up from their seats and stood in the isle and told them to back off.
Another time me and a mate were leaving a gay club and to get to the train station you have to walk through a dark alley. i guess these guys had followed us and started shoving us around saying stuff like "look at these fags" I was scared i was about to be gay bashed [lol wtf iam not even gay] so i started laughing, reached into my pocket and said who wants to get stabbed first? I doubt i was very convincing because i was scared, but it made them back off for a second and then we ran to the well lit, populated and cctv area at the train station, but i was worried they would come back and didnt want to wait 1hr+ for a train so i called dad to come pick me up lol.
Now when i travel at night i carry a small, extremely bright defence flashlight, you are supposed to shine it in their eyes then run, or i guess you could get a cheap shot in while they are blinded if running isnt a possibility.