FWIW:
When it comes to folders of the size typically carried here in the US, for many years I preferred a hammer grip for the knife and therefore chose knives with handles that favored this grip. Part of the reason that I preferred hammer grip was that I got (and probably still do get) better results with it in what in DBMA we call "Sport Knife Dueling". Because I suspect the SKD mindset informs the thinking of many people in martial arts for Real World application more than they realize (which was certainly the case for me) I'd like to share a bit of my own evolution here.
I begin by making clear that, despite the playfulness of the name, I do not make fun of SKD. SKD was a staple of my training some 25 years ago with Paul Vunak who used it for the development for certain important attributes such as footwork, timing, reflexes, etc. Furthermore, in the Dog Brothers we have always used SKD as a way to open our "DB Gatherings of the Pack" for additional purpose of kicking the day off, getting fighters warmed up for the stickfights, letting fighters assess each other a bit before stickfighting, etc. (The Euros do not do SKD at their DB Gatherings.)
In short SKD dueling can be lots of fun for young males into ritual hierarchical ritual combat AND it can serve quite well in many situations which force one to pull a knife. And these knife skills can be very directly applicable to the real world should one need to use a knife to keep threat at bay-- though do note that brandishing a knife at an unarmed person can present interesting legal questions. I'm not saying these questions can't be answered with the right fact pattern e.g. a middle aged desk jockey being menaced by a guy whose face is covered with MS-13 tattoos intuitively seems to me like a relatively easy sell
but often the line between legal and illegal brandishing can be quite blurred.
But I digress , , , Returning to the discussion,
That said it does present interesting challenges for those interested in using this training method for real world application because IMHO what we do in the adrenal state of ritual combat will tend to appear in real world combat as well. (This is precisely the reason I develop our "Kali Tudo" tm-- so we can adrenalize our empty handed fighting with Kali Silat with the result that our unarmed and armed fighting are the same idiom of movement.)
But what if the worst case scenarios of the real world feature behaviors other than those assumed by "proper" SKD?
In the real world two people facing off with real knives drawn is really rare. As the actors here in Los Angeles would say "What is the motive here in this scene?" What would motivate someone to stay and have a knife fight? And how likely is it that the other person would be equally motivated? In prison I suppose leaving might not really be an option, but most of us are not in prison-- and in prison it is usually an ambush, often by superior numbers, anyway.
If we answer the question by assuming two men both in a killing rage e.g. in prison or on the battlefied, then we are likely to see, in the immortal words of someone with whom I once had an interesting conversation, the behavior pattern of "Pump him until he is dead, then bind your wounds" (Hereinafter "Pump and bind" or PAB). The problem though for SKD is if we bring PAB to it then we are not developing the attributes intended by the training nor or we acting rationally like the semi-normal people that we are for KD is not something rational people do in our time and place in our culture.
Thus in SKD we are left with the inherently blurry lines concerning the definition of realistic behavior for it. Most people will leave in the presence of a knife, but if we assume staying e.g. a desperate robber, then we can say most people would leave after getting slashed or stabbed. On the other hand, of the kind of people who in this world are genuinely willing and motivated to engage against a knife, then most of them will not leave after getting wounded, for their mindset is Pump and Bind-- they expect to be cut and stabbed and to survive the process of killing you , , , or they don't care if they die as long as they kill you.
Good luck and my rules of engagement (avoid stupid people in stupid places doing stupid things and what your think of me is none of my business) have combined to my having absolutely no personal experience in this whatsover. Success! That said my readings, conversations with those not so lucky, and various youtube clips have persuaded me that many people do not realize that they have been slashed or stabbed until after the fight is over. This can include even mortal wounds.
Thus we can have someone of evil intent unstopped and undeterred by what SKD might consider "good scores". In SKD I might be busily defanging the snake by slashing at the arm of my opponent but if some cranked out gangbanger in colder weather wearing heavier clothing is coming to get me, well then those slashes that I thought would stop him and keep him outside my bubble might not work.
Thus it is that I have come to the thinking that when using a small knife (e.g. one that is not going to lop off hands) that the power and impact of the strike matter and for me ice pick does a better job than hammer grip.
Thus for Kali Tudo, I look principally to double stick and double ice pick knife.
