The typical methodology of any foci is if get broken in the meat it gets broke in the astral. The enchantment ends.

But there is a possiblity that though this is generally the case it may be a perceptual rule not a natural law.

For example: some astral objects without physical form exist. Some like alcheal mainifest and even materialize.
An astral shadow continues dispite the destruction or partial alteration of the physical.

It is typical fantasy fair that the broken sword must be reforged. A symbol of renewed strength from the age of glory etc

But consider, what if an enchantment left a memory in the astral, the broken sword of legend is whole in the spirit realm and so functions as such in astral combat, it potency dimmed but not forgotten.

Perhapes the tomohawk blade simply needs a new haft in the physical world but remains complete in the astral due to the ancient spells.

If this is to much of a stretch, perhapes a middle ground. The magical dagger is a mightly claymore on the astral.
(I would suggest that you still pay a claymore bonding cost. Though not much good in the physical hoop kicking it is easier to walk around with and is still big and pointy in astral hoop kicking. )

This leads to the conjecture that laying aside the concept of form equals function in favour of symbolic equals function; (A standard concept in magic both fantasy and real world belief structures) it would be possible to create a focus that is useless on the physical but exists in the astral.

A oracalchum hilt lacking a blade for example, save its astral form is a full broadsword.

Now we must stop before we reach the, "Quail mortal at my tooth pick of DOOM!"
Or "My sword shaped tie pin is a two handed sword on the astral!" (Yeah ~I bet you say that to all the girls...)

If you like that sort of thing you may even have a blade that materialises as and when the ref calls.

My instinct here is that the first point be reserved for the mighty magical plot device.

The possibility of a custom researched and made, symbolic astral weapon focus (minus the materializing blade)- I think I will allow discourse to sway me.

Comments?

i like the way you think. it makes sense to me. ill probably use these concepts in my stories.

Thanks. I was inspired by Egypishain shabasti/ umshabasti and tang tomb dolls/ terracotta army.

In my game I have a academic meta magic, researched for pure thaumalotogical research, that can create astral objects. Researching the game balance from the fluff and crunch on astral phenomina lead down the avenue of thought.

There are plenty of house rule spells to create astral weapons but this for me breaks the whole point of a weapon foci function and game balance. I want to explore the grey zones of magic without breaking the game world or game balance.

I would reserve this for legendary (aka Unique) Enchantments. The Sword of Pendragon may have the gall keep kicking astral hoop but a generic Rating One focus is just kaputski.