The information on Ziu (Tyr) is not enormous in volume, but we do have some in oral lore and in writings by an historical folklorist. There were also some dots to connect (like a practitioner describing how he would appeal to the North Star for clients in need of justice). He was hardly alone in recognizing the North Star as something unique. Other sentiments expressed about the North Star included (paraphrased) "the axis/pillar of the world," "the star that keeps the world going around," "Sky Father," and, my personal favorite, "the left hand of justice."
The name Ziu did not come up as frequently in interviews with practitioners of Braucherei as Holle or Dunner, but it did occasionally for aiding clients in legal or social matters. The psychological consultation aspect of Braucherei is not as well known as the physical healing aspects, but the healing of the mind is part of the practice. Wudan is the deity (or, for syncretic practitioners, "helpful entity") most commonly appealed to for spiritual quandaries; Berchta or Holle are most commonly appealed to for mental disorders. It seems that the appeals to Ziu were for issues needing definitive clarity, justice, and instances requiring "no shade of gray."
The pages in the Introduction section at the beginning of Fogel's Beliefs and Superstitions of the Pennsylvania Germans are the most interesting in the book from the perspective of a Heathen. I should disclaim, though, that some of what is written there regarding some deities matches tangentially (or not at all) with our current understanding. There is some conflation of some deities (Ewicher Yeeger and Wudan, for example) and only a passing reference to Holle ("Hulde") and Harke. Still, though, the book attests to the awareness and functional presence of the deities in Deitsch culture, and, for a non-Heathen to be writing of them (and other things, such as sacrificial rites) in 1915 is worthy of remark.
On page 11 he writes, "Tuesday, named for Tiw, Ziu, Tyr, and Thursday, named for Thor, Donar, are the favorite wedding days in most of Pennsylvania German counties." This, by the way, is very much true of Plain sectarians, though I doubt they possess widespread knowledge of the root of those days being chosen for weddings.
Tuesday and Thursday are good days to drive cattle, though the first drive of the year is to be on a Thursday (this is still a common practice). After that, the protected days are Tuesday and Thursday, and it considered inauspicious to drive them on a Monday and bad luck to drive on Wednesday or Friday. Fogel's book, by the way, reflects these superstitions indirectly.
Red is the color associated with both Dunner and Ziu, though Fogel's work only reflects the sacredness to Dunner. In either case, red is one of the old wedding colors (and has been revived). The other color is blue with an association with both Frigg and Holle, and it is interesting to note that blue is also the common wedding color among the Plain sectarians. Friday is also a common wedding day in some areas. Hence, in Urglaawe practice, red and blue are the dominant wedding colors.
Of particular relevance now is an association between Ziu and the Faschtnachtskuche, which is the deep-fried potato doughnut widely made and consumed on Shrove Tuesday (Fogel reflects this but with some serious conflation with Dunner and Oschdra. We've long theorized that Shrove Tuesday (Fasching/Mardi Gras) celebrations are rooted, at least partially, in Wild Hunt depictions (going from dismal or spooky to colorful and joyous after the NewYear) and that the time of the Entschtanning ("emergence") is a twelve-night observance beginning on the current calendar on Groundhog Day.
Although the Faschtnachtskuche are strongly associated with Ash Wednesday traditions within Christianity's own paradigm, there is some evidence (even reflected in Fogel's book) of cake-types of offerings related to fertility or promise that predate the Christianization of Europe.
The link between Ziu and the Faschtnacht is rooted in their serving s a point of community (people make them and share them widely), and the diligence in baking them reflects right-mindedness. There is also a major element of an investment of trust that better times are soon coming and we can splurge a bit on the food in storage. Also, eating a Faschtnachtskuche is said to ensure that you will live a year longer.
The Faschtnachtskuche could also be associated with Frigg (the act of baking causes rising and growth) or with the Idise and motherhood in general. This is most certainly appropriate for Entschtanning as Frigg and the Idise are honored specifically in this time. Perhaps we should consume the doughnuts on the last Friday of Entschtanning.
In herbalism, there are several plants that one could go to in order to consult on matters that relate to issues to which we appeal to Ziu. Most notable among them is the highly poisonous Aconitum napellus, which is known in English as Wolfsbane, Monkshood, or Tyr's Helm. In Deitsch, it is known as Eisehut, Himmelvaddershelm ("Sky Father's Helmet"), Himmelvaddersbeidel ("Sky Father's Scrotum"), and likely others. Although this plant has been used for gout and in ointments (including some occult-types) over the centuries, it is highly poisonous (even deadly) and I would not recommend ingestion in any form. it is more common (and safer) to engage in esoteric practices such as Blanzeschwetze ("plant talking" or meditation). As a matter of prudence, I would recommend wearing gloves when handling the plant. Also, I keep a few snips or scissors that are used only to harvest poisonous plants, and I wash them when finished.
Now comes the esoteric part...
Wolfsbane's spirit is very serious and will listen to appeals. However, it has a low tolerance for for chicanery or especially for "crocodile tears." In short, if someone planted a nasty situation and is now reaping that harvest, the plant will refuse to engage with the mediator. However, the plant will work with those who have taken steps to correct their course of action, and it will go out of its way to aid in the health of the faculties of those who have been clear victims of injustice. It is one of only a very few plants I have encountered in the last few years that will sacrifice itself to lend energy to those engaged in just or "macro," big picture types of causes. That, of course, is consistent with the understanding of Ziu.