Melee and snipe can't be done at the same time. Or it can be done but both will be subpar.
As for relics: melee damage max at 30/30 seraph melee max at 35/35 weapons damage max at 30 BUT you are better of with a vladofs allegience dam+30 and recoil reduction +53% (and razrez vladof's sniper of course)
you can have a melee build slightly tuned to sniper with:
- a 11 RoF rapier (slag is the best, harder to come by too), - a razrez vladof of whatever element - vladof allegience with Recoil reduction 53.5% acc Recovery 100.0% and rising shot to +5
a ninja class mod +46% light be usefull to but you can go for a +6 in rising shot. Problem is, you'll get out of sniper bullets quickly.
I have a +44/70 allegience relic and it makes the rapier (a 11 rof fire one) one of the deadliest weapon i have, almost as good as my caustic rabid shredifier when the vladof allegience relic is not used with it since what it lack in rof (11 against 15), it keeps it up in precision (half the mag is spot on, wait a second, empty the rest of the mag).