Not to necessarily rain on your parade, but to be taken seriously for delve bosses..
For brd, you're going to need a minimum 95/99 G-horn and 90 Daur.
For mnk, you're going to need minimum Rigors, a really good acc set, a pdt/dt set, and mantra.
For scholar, you're going to need an Apajamas II and a good stun set.
Nobody really needs blm or thf for delve bosses. Th doesn't really effect enough to warrant the dps loss from bringing a thf.
For your sam friend, a masamune really isn't going to cut it (sorry). For bosses that sams are brought to, it's likely usually because of Muras' situational usefulness, and when they're not using Mura they should have an Uguisumaru.