There is a very famous fencing school/style that has two leading disciples.
People say that these two are the 龍虎 of the school.
The translations I found ("heroes, dragon and tiger, mighty rivals") do not
suit them well.
"Heroes" is exaggerated. They will kill men for the first time a bit later, and it will be their first meritous deed, so...
"Dragon and tiger", well...maybe intended as powerful warriors?
"Mighty rivals" is off too. They are comrades, they train together, work together and so on. They are more like brothers than comrades and there's no fierce rivalry between them, at least in the story this never comes out.
Ryuhko...maybe something like two people who show a lot of promise in some field?
2 mighty peers? Would it be too simple? I can't think of anything better atm.