Oh and yes, both line does fray and is super slick when new and knots are a pain in the ass. Even FG knot. So it's a no no if your leader choice is less than 15 lbs. All other line to line knot besides FG, PR knot and Bimini are relatively weak..50% with Nanofil.
I normally use 25-30 leader with Nanofil 10-12 and Fireline 8-10 lbs. I can hand off the spinning reel to my kids and he'll never bother me with windknot and tip wraps when jigging artificials. Unlike braid, it does fray and loses 20-30% strength but guess what, worn out Power Pro, Pro Spec, J braid, Stren Superbraid, Suffix 832, Samurai braid....every single braid loses 20-30% of its true ABS once the coating wears off and it starts to get fuzzy.
Your 14 lbs actually breaks at 26 lbs. Your FG knot strength should be at least 20 lbs. Tie a 25 lbs leader for testing and attach that to a 15 lbs dumbbell. You should be able to easily lift that dumbbell off the ground. Wear a safety goggle when testing. It will be hard to tie 14 lbs Nanofil to leader less than 15 lbs using FG knot. Scrape the coating off first.