As we know, anti-particle will be annihilated by positive particle and release a mess of energy even though barely. And also it has a big advantage, the process is clean, it hasn't radiation. So I have a tentative idea of anti-matter weapon as below.
In a vacual shell, isolated layer separate the positive particle and antiparticle. Spinning the antiparticle to avoid it touching the shell. The isolated layer will be destroyed when the shell collides with something or it can be designed for self-destruction by timer or something else, the positive particle will through it and collide with antiparticle to release the massive energy.
But there are also many difficulties to make it come true. First at all is how to create so much antiparticle and hold it for a long time. We can create a little of it by an accelerator in lab and hold it for a few microsecond, but the quantity is not enough and holding period is not enough as well.
