The ability for titanium to make a good blade can be greatly improved depending on what it's alloyed with; similarly, iron isn't known for good edge retention either until it's alloyed with carbon and other elements to make steel. However, titanium alloys are still largely unexplored territory for blade use. When someone says "titanium" can't hold an edge, it's always in reference to the ubiquitous 6al4v (grade 5) which comes from the mill as a softer, impact and stress-resistant form for structural use. 6al4v is specifically designed to not get too hard, hence the tungsten carbide edge treatment, but even without tungsten carbide it can be improved and work great for large chopping blades that are less dependent upon sheer hardness for performance.