This really embodies the mourning fashion rules of "black and silver, no gold, no colors, nothing shiny". Clothing and jewelry for deep mourning involved black crape and bombazine because they weren't shiny like silk, and jet beads instead of shiny jewels. In this brooch, the vulcanite is polished but matte, and the "silver" metalwork is actually a silver/gunmetal color, and it's also as dark and as matte as possible!
Garland - representing the triumph of the soul over death and the realization of eternal life.
Grapevines for mourning are deeply rooted in history and symbolism, with vines and leaves frequently found in historical cemetery monuments and Victorian-era mourning jewelry. They symbolize rebirth, the triumph over death, and the joys of the afterlife, as well as the blood of Christ in Christian tradition.
Eagle – Representing courage and possibly a military career.
Rose – Representing love, beauty, hope and goodness and associated with the Virgin Mary and the ‘rose without thorns.’ A red rose stands for martyrdom and a white rose means purity.
Forget-me-nots - Representing enduring remembrance, true love, and faithfulness. It served as a comforting promise that the emotional bond with the deceased remained unbroken, transcending death and keeping the memory of the loved one alive.
I'm not sure what the objects are on either side of the garland. Bells? Angels? My best guess is Tassels - symbolizing weeping, grief, and tears. In cemetery art and on woven memorial textiles, tassels were common companions to draped urns. They symbolized the passage from earthly life to the afterlife and the transitional state of grief. Tassels also act as a divider between the mortal and spiritual realms, often indicating that the deceased has successfully passed into the next world.