Yesterday, our daughter invited my wife and me to visit her after-school robotics club. I was quite impressed by how her teacher handled the problems that the students encountered while working on their codes and mechanical designs. When they reported a problem, he would ask a variation of this question: “What element do you think needs to be changed?” I think this question is incredibly powerful, because it simultaneously encourages the students to do two things: to critically analyze the current state of the project and to identify the next specific step in the solution.
For example, my daughter was writing a code for her Lego EV3-based robot to undergo a mission consisting of driving to a specific spot on the table while avoiding the specified boundaries, performing a 720-degree turn while keeping one wheel inside the target spot and returning back to the starting area. She had trouble with returning back to the base, but with the above prompt from the teacher was able to identify the problematic lite in her code – the robot was turning a bit too much during one of the turns on the way back – and to fix it. Another student was having an issue with the design of his robot – it was getting stuck on its way to the target spot. The same question helped him to realize that the wheels were catching on the base, and the solution was quickly found.
I would certainly like to borrow this question for my own use – in the interactions with my students in the courses I teach and in the lab, with my daughter (helping her to solve the problem at hand without offering a ready-made solution) and directed to myself as a means of teasing out a constructive way forward in whatever I do without being overly critical for the apparent failure of the current state of affairs (the question asks to think about one specific aspect to be changed, not the worthiness of the entire project).
A katana, or any Japanese-style blade for that matter (as well as some Middle-eastern blades like in the image above), is similar to a pencil in terms of the principle of its physical construction. 
A company logo is intended to convey a distinctive identity, but achieving this on something that would be printed on something as small as a postage stamp or as large as a billboard is not trivial. Perhaps, it is not surprising that distilling the principles of a good logo design to a concrete recipe is challenging. After all if it would be easy, everyone wold be a great logo designer. Still, some basic principles can be discerned by studying the common features of famous logos.