The advantage of having no core in a dagger is that in many systems it can be a throw weapon. No core means you have in essence a lump of foam covered in latex, and while not the softest thing in the world it is unlikely to do any great harm.
From the point of view as being used as a prop weapon is that the foam has virtually no rigidity.
I’ve made a couple of coreless daggers in the past the first one although not bad was a little on the large 
side, so I never really used it and eventually removed all the latex to try out an idea I had for carving the foam.
The second was the stone/flint dagger in the right of the picture to the left. It was an experiment which worked really well and used up an off-cut of foam that was otherwise destined for the bin.
The current one is a little more ambitious and has the added factor that I’m making it for someone else, and not having made anything for anybody apart from my son and I means I’m even more nervous about the result.
Coreless Dagger Blank
It’s based on the dagger in this photograph on wikipedia. A fine looking celtic dagger with anthropomorphic handle. The blank was relatively easy to prepare using four layers of 6mm foam. Well truth be told this was the second blank. The first went horribly wrong during the dreaded cutting phase, which resulted in a nice handle but a blade like a stiletto, or possibly the first larp safe tooth pick. As I’ve said before the cutting out the blade bit is the part I fear most. In theory it should be easier with a dagger, shorter blade, less to cut. So using the last of my foam I started again. Hopefully this time it won’t be such a disaster.
