I don't think that there are any specific laws written about knives. It used to be that you could carry anything. However, certain political problems have caught up with us, and now there are metal detectors everywhere. In private places like clubs, it is up to the owner's discretion--usually left in the hands of a security guard. In a public place that is guarded--like a government ministry, museum, holy site, or some such--it will be found by the security people and the decision will be based on the decisions of the directives received from the chief of security, who has almost certainly drafted some directives, so it won't be completely arbitrary. In many cases, you will not be allowed to enter with a sheath knife or large folder. If you want to keep it with you-- something about 2" should be ok. Slipjoints are probably best.
If you have a carry permit for a pistol, then don't worry about anything.
In general, though, small knives are best for reducing paranoia on the part of security personell-- and there is plenty of good reason for paranoia in Israel.