On the search screen of Epicyon there are a list of hashtags, which you can select to see the corresponding posts. They're not exactly trending hashtags, just ones which have appeared within the last couple of days. Depending upon how many people you're following this can potentially be quite a large list.
So to make things simpler I've added the ability to categorize hashtags, which groups them under category headings. Similar to putting files into a folder in an operating system. The search screen can then show just the categories which have recently appeared, and you can then select them to see the hashtags within those categories. It simplifies the search screen, and helps to impose some order upon the chaos of hashtags.
Assigning categories is easy. If you select "Show All" on the search screen then you can see all the hashtags. At the top of the screen for each tag you'll be able to enter a category. If you do this enough then over time your hashtags will become neatly categorized.
Some default categories have been set up for English language, but since there are many possible ways of categorising the world you can overwrite these if you want different categories. The categories for your instance are published as an RSS feed icon in the right column, and you can subscribe to the categories of other instances by entering their feed URL in the newswire settings. This should enable allied instances to build up appropriate categories for their purposes.