Basically the blades are similar to cutter cartridge [link] . But each blades is equipped with explosive. When the blast dagger is used to stab the enemy, the tip of the blade will snap and after a while it will explode. Dealing major damage to inner structure.
Wow, I think I call that settings of a mech, which can not be seen unless the author explain to them viewer, like transforming, inner parts, unique uses of some parts, etc... I feel sorry if I did not get the exact mean of this word.... but seems Bandai uses that in their explanation, as ギミック(gimmick), some how same mean as “mechanism”