Is it good idea?
Knife self-defense? Well, knife (as any other edged weapons) is NOT suitable for self-defense.
Knife is a deadly weapon. Using it as a non-deadly is a highly advanced skill that can be demonstrated only in case of significant technical and tactical superiority of defender versus attacker.
Legal goal of a self-defense by using force is very strict and explicitly defined (see this link for an example:
Only very narrow limited circumstances can justify using deadly force and those circumstances will rapidly change during the confrontation itself: so, if you was attacked with a weapon and with your first defensive knife strike you immobilized attacker’s only armed arm (with ‘bio-mechanical’ cut), then the second knife strike that cause body injury will not be seen as in self-defense because your first strike removed the present and immanent danger. So, if you will kill your attacker with more then one successful knife strike, or with a knife strike while controlling his movements by any other means, or with a knife strike while you put him in disadvantage by any tactical means, or with a knife strike when you was able to retreat from the proximity of hostility, or anything alike, you will not be able to use legal self-defense argument and most likely will be convicted in felony homicide or manslaughter of some degree.
Is state prison what you want for your living arrangement? If not, use your knife as a kitchen, camping, or craft tool only. You can also put it on display in a glass presentation box.
Best discussion about self-defense in general and about (not) using knife in self-defense is on the site of
Macs "Animal" MacYang