Túrin Afflicts the Afflicted

[Inziladun]

It seems curious to me that Túrin's story includes characters with features not common in other Middle-earth tales: physical disabilities.

We do see Thráin the Dwarf losing an eye while fighting Orcs and getting a wound in his leg, and there are possibly other mentions of battle injuries.
However, in Túrin's case, he interacts with no less than three persons who have incapacitating physical issues unrelated to fighting: Sador "Labadal", who apparently cut part of his leg or foot with his own ax; Gwindor, the Elf of Nargothrond, who due to his torment and labor in Angband, was so old and weak that his own people could have thought him an old Man (CoH takes it a step further in saying Gwindor had lost a hand in his escape from Morgoth); and Brandir of Brethil, who was said to have gotten a leg injury some time in his childhood that left him with a limp.

Now, those three have entirely different back stories, and different stations among their people. All seem to have in common though a store of wisdom and patience. They try to give Túrin good advice, which, it could be argued, if he had taken, could have helped him avoid Morgoth's designs.
Also, Túrin steals the hearts of the women loved by two of them, Gwindor and Brandir, and both women die.
Lastly, Túrin causes the deaths of all three: two, Sador and Gwindor, indirectly, and Brandir by overtly killing him with a sword.

All this seems a strange coincidence, if that's what it is. Or, did Tolkien mean something by putting all that in Túrin's tale? Was it a statement that a strong body and fighting prowess ought to give way more often to gentle wisdom? That in Arda, it really is the "weak" who are strong?