Struggling to see how this knife design could be an advantage in most circumstances:

• Very little space behind blade for tang- likely to break off from mount
• weapon takes up a great deal of space when not in use (for any weapon, you’re normally carrying it rather than using it than 95% of the time you have it with you)
• compels user to adopt only a single grip requiring significant grip strength simply in order to punch with sufficient force whilst not breaking your wrist

Surely when it comes to armour piercing something like a stiletto would be much better