Iron tsuba of round form decorated with design of dragonfly in negative openwork (in-sukashi). It may be Ko-Tōshō (old Tōshō) or just Tōshō school, without a 'Ko'. Probably the dragonfly here is used as a family crest (mon). Muromachi period. Dimensions: Height: 95.0 mm. Width: 93.6 mm. Rim thickness: 2.1 mm. Center thickness: 2.3 mm. Nakago-ana: height = 30 mm, width = 7.8 mm. A dragonfly design is described by John W. Dower as following "During the period of feudal warfare, the dragonfly is reputed to have been am especially popular design applied to arrow quivers, and some warriors adopted it as a family crest. One reason for this was the insect's alternative names of katsu mushi and shogun mushi, both meaning 'victory insect'." Merrily Baird is even more talkative regarding the matter: "The dragonfly (tombo) in Japan is emblematic of martial success, as various names for the insect are homophones for words meaning "victory". The dragonfly is also auspicious because references in the Kojiki and Nihongi link it in both name and shape to the old kingdom of Yamato. This legacy has led to the use of dragonfly as an emblem on arrow quivers and as family crest. It also appears occasionally in conjunction with such imperial motifs as the chrysanthemum. Used in a context devoid of historical associations, the dragonfly is a seasonal symbol of late summer and early autumn." Dragonfly was an extremely often motif for the tsuba in all times, primarily in earlier times, before Tokugawa pacified the nation. The same motif is used on Ōnin tsuba in this collection:

Iron tsuba of round form with two overlapping triangles (uroko) motif  in openwork (sukashi). Triangle patterns usually associate with 'fish scale', mon of Hojo family (and others). Edo period or later.

Size: 71.4 x 70.2 x 5.2 mm.

An association with the Star of David is doubtful if not impossible.  

Iron tsuba of six-lobed (mutsu-mokkō-gata) form, with six wild boar's eye shape (inome) openings (sukashi). Hitsu-ana and the entire perimeter of tsuba have typical for this school raised rim. Lobes are decorated with landscape motifs in low relief carving (sukidashi-bori). On the obverse: A hut under a full moon, Shinto shrine gates (torii) with pines and a full moon, rocks, a large pine tree, and a temple (pagoda) surrounded by rocks and waves. On the reverse: waves, fishing boat, wild gees in flight under full moon, maple, hexagon (tortoiseshell, kikko) with a dot inside and a dot outside (inclusion/exclusion symbol), and chrysanthemum (the last two may be family crests, mon). Kamakura-bori school. Late Muromachi period (1514-1573). Height: 64.2 mm, width: 74.3 mm, Thickness at seppa-dai: 3.2 mm, at rim 2.6 mm. Weight: 62.8 g (light). NBTHK old green certificate №561: Tokubetsu Kicho  - "Extraordinary Work". A look-a-like tsuba can be found at the Compton Collection, part II, pp. 14-15, №17, though his tsuba is more massive (80 x 84 x 4 mm). NBTHK paper says that the motif is Hakkei (八景), i.e. "Eight Views," so several interpretations are possible (the original Chinese ones, Omi Hakkei, etc.).  However, most likely it is the 'Eight views of Omi' (近江八景  - 'Omi Hakkei'). Why the artist selected a 6-lobed form for depicting 8 views remains unclear, and thus we are in our right to raise the question whether the motif is indeed Hakkei. The term Omi hakkei (eight views of Omi) refers to painting or print sets which illustrate life on the shores of Lake Biwa in Omi (now Shiga Prefecture). The model for such paintings came from China, where, from the eleventh century onward, painters had produced eight views of the Hsiao and Hsiang lake areas of Hunan Province. The themes, which follow the original Chinese models, are: geese descending to land, returning fishing boats, clearing rain, a snow-covered evening landscape, the autumn moon, night rain, a temple bell at evening, and the glow of sunset. Japanese artists have also used the eight-theme approach for other parts of country - including cities - and applied it to subject matter other than landscapes. [Merrily Baird. Symbols of Japan. Thematic motifs in art and design. Rizzoli international publications, Inc., 2001, page 308-9]. Japan Encyclopedia by Louis Frédéric also mentions Omi Hakkei as "Eight landscapes of Omi", and states that this theme was often cited in poetry after 1500. It is likely that the tsuba in focus is designed under the influence of the theme popularity in the 16th century. The theme was effectively exploited by prominent ukiyo-e artists Suzuki Harunobu and Utagawa Hiroshige in the 18th and 19th century, respectively. These are the eight scenes of the theme (see Wikipedia):

• Returning sails at Yabase (矢橋の帰帆) - Yabase. Yabase is an old harbour on the east side of the lake. Near the Tokaido, it was used for a shortcut to Otsu by boat.
• Evening glow at Seta (勢多（瀬田）の夕照) - The Chinese Bridge at Seta. The long bridge across the Seta was used by the Tokaido. In the background the "Fuji of Omi", the Mikamiyama. It is just above 400 m, but indeed well visible.
• Autumn moon at Ishiyama (石山の秋月) - Ishiyama Temple. The Ishiyamadera was located on a hillside next to the Seta River. It got his name form the strange rocks on which it is built, partly on supporting beams. A hut at the upper end of the site allows a view of the lake, and the moon.
• Clear breeze at Awazu (粟津の晴嵐) - Awazuhara. Awazu is well known for its pine wood, Awazu-ga-hara.
• Evening bell at Miidera (三井晩鐘) - Mii-dera. Miidera temple was built in the 8th century. Its famous bell is one of the "Three bells of Japan", the other two being those at Byoodo-in, Uji and at Jingoji, Kyoto.
• Evening rain at Karasaki (唐崎の夜雨) - Karasaki Shrine. Karasaki is a small cape with a single large pine tree, a hitsu-matsu.
• Wild geese returning home at Katata (堅田の落雁) - Ukimido. Alighting geese cannot be seen always, however the little temple near Katata in the square hōkyō-style, detached from the lakeside, connected by a bridge. The first part of the name uki is the same as in Ukiyo-e, meaning floating. Midō means temple.
• Evening snow at Hira (比良の暮雪) - Hira Mountains. The Hira mountains on the west side of the lake experience the hard winter, when the winter monsoon brings much snow from the continent.

In any case, as a conservative, I say that it is a landscape motif and a late Muromachi period work, rather than Omi hakkei motif and a mid-Muromachi work.

Shingen school tsuba with woven wire pattern. Iron core, woven brass wire. Height: 72.5 mm; Width 69.8 mm; Thickness at seppa-dai: 4.0 mm. Weight 88.8 g. Late Muromachi, 16th century. SOLD http://varshavskycollection.com/shingen-tsuba/

Iron tsuba of round form inlaid with brass, copper, and shakudō wire fastened to the surface with metal staples (mukade-zōgan); Scalloped brass inlay around the rim. Early Edo, 17th century. Height: 84.8 mm; Width 84.8 mm; Thickness at seppa-dai: 3.7 mm. Weight 161.6 g. Design is thought to resemble a centipede. "Centipede-like inlay (mukade zogan) of alternating iron and brass staples produce an appearance that was particularly favored by Takeda Shingen (1521-1573), one of the most powerful warlords of his time. The centipede is sacred to Bishamon (God of War) and especially propitious for a warrior. Shingen type, 16^th century.” [The Peabody Museum collection of Japanese sword guards with selected pieces of sword furniture, by John D. Hamilton. Photographs by Mark Sexton. Salem, MA, 1975.] See also: http://varshavskycollection.com/shingen-tsuba/