Shard Weapons and Tools

The shards are not destructible. This makes them useful for industrial purposes. However, their quartz-like shapes limits that usefulness (such as, they aren’t very good at being nails, or armor, or building materials). What they are good for is spearpoints, arrowheads, axeblades, and picks. Some crystal clusters might be able to be fashioned into a dagger. Weapons fashioned with shards would likely resemble Aztec obsidian weapons, without the sharp edges of the obsidian.
People will be very attached to these weapons, so they will be made with lanyards to reduce the chance of them losing them. People will be unlikely to want to lend them to anyone else, or put them away, or drop them. Or, in the case of arrows or spears, it may take a Will roll to actually loose them (and thus “giving” them to an enemy).
Arrowheads: Assuming that anyone having these shards would be able to “get rid of them” by shooting them at someone (which might take a Will roll, since the urge to hold on to them is strong), consider them “Very Fine” bodkin points, giving them +2 damage. The “downside” is that someone wounded by one might not want it removed….Usable for any draw length of arrow, or crossbow bolt.
Spearpoints: Depends upon shape, although most would be considered “winged” spearpoints due to the random crystal structure of combined shards. Many also wouldn’t be all that sharp, again due to the crystalline shape, and thus not suitable for weapons.
Swords: These would be metal, with the shards socketed into the sides, acting like “teeth” along the edge of the “blade”. Although this makes them more like morning stars rather than swords, as they don’t have an edge, just a bunch of spiky bits. Treat as a mace, but uses the Broadsword or Shortsword skill (due to edge alignment issues), and damage is Piercing (pr). These will be rare; at first they were a more common weapon type, but it was determined that having the shards only at the tip was more effective, leading to …
Axes: Like the swords above, except the shards are only at the top handspan or so of its length, resulting in better damage. Treat as a Very Fine Axe (+2 damage).
War picks/Warhammers: Similar in construction to the shard axe, but with only one long shard. Treat as a Very Fine pick (impaling, +2 damage). Note that despite its name, a warhammer is not a bludgeoning weapon, it’s impaling.
Polearms: Basically a war pick with a longer haft. See Ge, and Ji (a Ge with a spearpoint). Treat as a halberd, but does impaling damage. Very Fine (+2 damage).
Daggers: Treat as a rondel. No edge, does impaling damage. Not super sharp, so unlike the other weapons with moment arms, doesn’t do the extra damage.
Hammers: Yes. As in tools, not weapons. A shard, attached crossways to a handle (presenting a flat face) would provide a nice, indestructible surface to work with.