Trinc doesn't need much of a nerf its not bad as it is. People just sail it because it has alot of 32pd carro's that hurt and doesn't cost a permit. If you know how to fight a trinc they lose, its as simple as that.
Endymion could do with a slap though because its just better than many 5th rates at everything. You can easily get it to 15.5 knots and it has 24pd longs which shred most other 5th rates. Also the HP is a bit ridiculous. According to whoever he is called map, after the endy and trinc the next highest HP on a fifth rate is what, the Santa Cecilia with 7,900? Compared to the Endymions 9,965. Along with that the cannons the Endymion can carry is 28 24pd long and 20 9pd longs, compared to the Cecilias 26 12pd longs and 16 9pd longs. The HP difference and damage per broadised doesn't make up the 80 BR difference if anyone wants to even try and bring up BR. If the Endymion is to carry much stronger cannons than its other competitors, it shouldnt be able to go anywhere near as fast, but it can. So I would say either take SOME of its HP away and either lower the caliber of the guns, or, the one I prefer would be to nerf its manoueverability. Make it still hit hard and still be one of the tankiest fifth rates, but nerf its speed and turn rate so that it can't keep up with the smaller ones. It should be more of a ship that is ideal for taking in a sort of fleet to hunt other larger ships such as picking on Aga's and Conni's etc. but make it so that when it comes to the smaller fifth rates they can just run from it if they desire. If people complain at that then take a smaller ship, you have a range of fifth rates to choose from for a reason. It shouldn't be the way it is where currently one ship fills all roles once you get it which it currently is with the port bonuses and mods.