classic waka stream

I could not hold back
the tears that have fallen on
this robe of mine—so
I take it off and change it
for a keepsake afterward

Meaning
I could not hold back the tears that have fallen on this robe; so I take it off and leave it as a keepsake for afterward.
Commentary
Volume Eleven: The Beheading of Shigehira

　Shigehira was to be handed to the monks of Nara, and on the way he was allowed a last meeting with his wife, Dainagon-no-suke, who was living at Hino. She stood stunned at how changed he was, hardly knowing whether it was waking or a dream.
　Shigehira spoke through tears. Last spring I meant to die at Ichi-no-tani and was taken alive instead, and made a spectacle of, and now I am to be handed to the monks of Nara and killed. I had thought that if I could see you once more there would be nothing left to hold me here, so I do not mind dying now. I would leave you something, but I am not even permitted to take vows. He laughed at that, thinly; then, as if the thought had just come, he bit off a lock of the hair falling across his forehead and gave it to her.
　She said that after their parting she had thought many times of dying, but that so long as he was alive—which was not the same as being gone—she had lived on for the chance of seeing him once more; and that with today that too was over, and there was nothing to hold her in a world without him. She clung to him and wept.
　That robe is too shabby, she said; let me at least give you a change of clothes—and offered a lined under-robe and a white over-robe. When he had changed, Shigehira handed her the hunting cloak he had been wearing: even this may serve as a keepsake, he said; keep it. If you would write even one line, she said, it would mean more to me—and held out an inkstone. He took the brush at once and wrote this.

　Karagoromo, the Chinese robe, is a poetic word that in verse introduces "to wear," "to take off," "to cut cloth." Here the poetic word points at the actual hunting cloak he has just removed. The figure has become an object.
　Sekikanete is being unable to dam something back. Tears fall on the robe, and the robe is taken off and given away. A garment marked with weeping becomes the keepsake.
　In Volume Seven, Tadanori left a scroll of poems and Tsunemasa a lute. In Volume Ten, Koremori called his letter a keepsake. What this man can leave is a lock of hair bitten off and a worn cloak. Since he is refused ordination he cannot leave a religious name or a proper cutting of hair. The poverty of the keepsake measures the weight of the offense.
　Shigehira burned the Great Buddha Hall at Nara in Volume Five. For that he is denied vows, given to the monks of the south, and beheaded by the Kizu River.

sekikanete……unable to hold back.
karagoromo……a Chinese robe; a poetic word introducing wearing and removing.
nochi no katami……a keepsake for later.
nugi zo kaenuru……I have taken it off and changed it.
Dainagon-no-suke……Shigehira's wife.
kariginu……an informal outer robe.
jōe……a white robe of purity.
awase no kosode……a lined under-robe.
Hino……a place in Yamashiro province.
Nanto no shuto……the monks of Tōdai-ji and Kōfuku-ji.
Source
Heike Monogatari
Other