Other similar specimens can be found at:
Henri L. Joly and Kumasaku Tomita, Japanese art and handicraft, "Swords and sword fittings" section, sub-section “Inlays of Ōnin, Kyoto, Fushimi-Yoshiro, and Kaga Province”, Plate CX, #128: Iron, chrysanthemoid, thin guard with alternate petals covered with brass spots. Ōnin style. 16th century.
Japanese art and handicraft, Plate CX, #128.
Compton Collection, Part I, #7.
The same interpretation of the said heart-like symbol (aoi leaf) is given at Helen C. Gunsaulus. Japanese sword-mounts in the collection of Field Museum. // Publication 216, Anthropological Series, Volume XVI; Chicago, 1923; p. 54: "This mokkō-formed tsuba recalls the aoi form, perforated as it is with the four aoi leaves." It is possible that the "wild boar's eye" theory was developed by later scholars.
There is also a theory, supported by Graham Gemmell, saying that: “In simple terms Onin works are decorated Ko-Katchushi tsuba. … But, not content with iron alone, they began to decorate it with what was, in the early Muromachi period, a rare and valuable metal, brass. The Onin workers cut the design into the iron, using narrow channels, cast the brass, piece by piece, and then hammered it into the iron plate as though they were putting together a jigsaw. When complete the tsuba would be black lacquered exactly as the plain iron ones had been, the brass shining dully through it in a way that fulfilled the goal of shibui or restrained elegance.” [Tosogu. Treasure of the samurai. Fine Japanese Sword Fittings from The Muromachi to The Meiji Period, by Graham Gemmell. // Sarzi-Amadè Limited, London, 1991. An exhibition held in London from 21st March to 4th April, 1991]. The following illustration from Helen C. Gunsaulus. Japanese sword-mounts in the collection of Field Museum. // Publication 216, Anthropological Series, Volume XVI; Chicago, 1923; pp. 43 supports the idea.
Helen C. Gunsaulus' description of the dragonfly emblem is as follows: "This motive, the dragon-fly (akitsu), is generally accepted as a symbol of the kingdom of Japan, and the origin of the idea is traced to the legend recounted in the Kojiki and Nihongo of the Emperor Jimmu's view of the island from mountain top. He is said to have thought the kingdom looked like a dragon-fly touching its tail with its mouth. From this it received its name Akitsu-shima... etc."
Tears That Brought Bamboo-shoots From the Frozen Earth: Meng Zong Meng Zong lived during the Three Kingdoms Period of China's past. His father died when he was young, and he and his mother struggled to survive. One winter his mother was stricken with a serious illness, and craved some bamboo-shoot broth as medicine. But in the depths of winter, with snow and ice blanketing the ground, where was anyone to find fresh bamboo shoots, shoots that emerge only in the warm months? Nonetheless, Meng Zong, to avoid disappointing his mother, bravely fetched his shovel and went out into the white landscape in search of bamboo shoots. In the thicket he found only frosted leaves and green stalks coated with snowflakes and ice. Look as he might, there were simply no fresh shoots growing in the winter. The thought of his poor mother lying sick on her bed, waiting for bamboo-broth medicine, made his heartache. Uncontrollably, tears began to fall in rivers to the ground beneath the tall, emerald canes. Even now, as his tears flowed down, he kept a light of faith in his heart. If he was truly sincere in his search, perhaps.... Just then Meng Zong nearly tripped and fell over a sharply protruding lump of earth. He quickly knelt down and knocked aside the dirt with his trembling fingers. How uncanny! Underneath his frozen hands he discovered a bed of fresh, tender bamboo shoots! Overjoyed, he gathered up a coatful and carried them back home. The broth that he quickly set stewing in the pot soon cured his mother's illness. The neighbors, hearing the story, exclaimed that it was the strength of his sincere, unselfish, filial resolve that inspired heaven and earth to respond, and to bring up, out of season, the fresh shoots that cured his mother's disease. Before Meng Zong's prayers generated this miracle, it was normally considered impossible for bamboo shoots to grow in the winter. After the nmiracle took place, however, people were able to gather and to eat bamboo shoots all year round. The winter variety that existed hereafter became known as "winter shoots." The villagers were deeply influenced by Meng Zong's courage and devotion. They renamed the spot where the event took place, "Meng Zong's Bamboo Grove". We can now enjoy bamboo sprouts during the winter as well, and as we do so, it is fitting to recollect Meng Zong's outstanding example of filial respect, and reflect on our conduct as sons and daughter of our parents. A verse in his honor says, His teardrops transformed winter at the roots; Up from the ice crept tender bamboo shoots. Instantly, the winter-sprouts matured; Heaven's will: a happy, peaceful world.
Iron tsuba of round form with design of hatchet, snowflake, and triple diamond in openwork (ko-sukashi), and inlaid with five concentric circles of brass dots (ten-zōgan) and brass inner circular line. Sukashi elements outlined in brass.
Late Muromachi period. Diameter: 82.4 mm; Thickness: 3.0 mm The triple lozenge (or diamond) is similar to the one on TSU-305 from Sasano Collection # 15. Very old motif; as Sasano remarks in his book "...represents the unstable political situation at the time".Kokusai Tosogu Kai 5th International Convention & Exhibition, October 28-30, 2009 at NEZU Museum, Tokyo, Japan, on page 83 provides the following explanation of the triple diamond symbol: "The pine bark is the form of the Diamonds, "Bishi", mon, seen from Nara period, found on cloth stored in the Shoso In, and used primarily by the Takeda family. The form of Bishi mon [similar to ours] is called "Chu Kage Matsukawa Bishi", (Middle Shaded Pine Bark Diamond)."
A combination of hatchet (usually an axe) and a triple diamond (Matsukawabishi) alludes to the Nō play Hachi-no-ki (ref: Iron tsuba. The works of the exhibition "Kurogane no hana", The Japanese Sword Museum, 2014; AND Sasano: Japanese Sword Guard Masterpieces from the Sasano Collection. By Sasano Masayuki. Part One. Published in Japan in 1994.
NBTHK certification of 1968: "Kicho". Condition is relatively poor: rust, missing inlay, scratches.
While representation of the snowflake is rather standard, the meaning of the other cut-out design was initially less clear. Similar symbol was found at (1) "Kokusai Tosogu Kai, International Convention & Exhibition, September 24-25, 2005, The Frazier Historical Arms Museum, Louisville, Kentucky, USA"; on page 21 there is a photograph J-6 of a ko-tosho tsuba with "iris theme openwork"; (2) Japanese Swords and Tsuba from the Professor A. Z. Freeman and the Phyllis Sharpe Memorial collections. Sotheby's, London, Thursday 10 April 1997; page 11, lot 6 - a ko-katchushi tsuba of early Muromachi period fith "simple design of stylized iris". In both sources the symbol is explained as 'iris" (kakitsubata).
Freeman and Sharpe collections. Sotheby's, 1997.
Kokusai Tosogu Kai, September 24-25, 2005.
English translation of the book indicated above Nihon Tō Kōza, Volume VI, Part 1 by Harry Afu Watson, AFU Research Enterprises, Inc., 1993. Tsuba in question illustrated on page 14 and described as follows: " Tsuba mumei Ōnin. Tetsu ji maru gata ko-sukashi tsuchime shitate shinchū suemon ten zogan maru mimi. Brass suemon". My question remains: why such a text is called 'translation' while it looks more like transliteration of romanization? 
The Henry D. Rosin Collection №9.
Lundgren Collection №7.
The design is referenced in LIB-1359.2017 Japanese Swords and Tsuba from the Professor A. Z. Freeman and the Phyllis Sharpe Memorial collections, Sotheby's, London, Thursday, 10 April 1997; p. 18, item 37: "pierced with two large formalised butterflies..."
A Kamakura-bori tsuba of octagonal form, Momoyama period
Iron tsuba of round form with brown patina decorated with the design of a Buddhist temple bell (tsurigane) in openwork (sukashi), with details outlined in brass wire (sen-zōgan), the outer ring decorated with two rows of brass dots (ten-zōgan), and the bell details carved in sukidashi-bori as on kamakura-bori pieces.
Ōnin school. Unsigned. Late Muromachi period, 16th century. Dimensions: 88.8 x 88.3 x 3.0 mm. As per Merrily Baird, two legends are usually associated with the image of tsurigane, a large, suspended Buddhist bell: one is that of Dojo Temple (Dojo-ji), and the other is of Benkei stealing the tsurigane of Miidera Temple. Interestingly, this type of bell (tsurigane) is not described as a family crest (mon), while suzu and hansho bells are.
Iron tsuba of mokkō form decorated with inome (wild boar's eye) in openwork (sukashi) outlined with brass wire. The plate decorated with 3 concentric circular rows of brass dots in ten-zōgan. Center of the plate outlined with the inlaid circular brass wire (sen-zōgan). Some dots and the outline of inome on the face are missing.
Ōnin school. Unsigned. Mid Muromachi period, middle of the 15th century. Dimensions: 72.1 x 71.3 x 2.3 mm.
Robert E. Haynes Catalog of April 9-11, 1982, № 36.
