Hi Fernando,
An acute tip is absolutely necessary for a good thrust. Think about the armor-piercing weapons we see, starting with the flyssa and going from there. To pierce a surface, especially an armored surface, you need to have a spike. The harder and tougher the surface is, the more important tip geometry is, and the more important that force is transmitted properly. Otherwise the tip won't penetrate.
There's an informal discussion of this on
www.thearma.org, titled
There is no best sword.
Jim and all,
I remembered another reason for rounded tips. Since I'm making the pumpkin pies for Thanksgiving this year, today is when I start by chopping the pumpkins up (I cook from scratch, thank you). Just for kicks, I decided to use my nice sirupati kukri (from Himalayan Imports, and not an antique). As I was sharpening it, I remembered the other thing tips are good for.
On a kukri, the major cutting surface, and the only part of the edge that is hardened, is the sweet spot a few inches back from the tip. When chopping, you're never supposed to hit with the kukri tip, and the major use for the tip is to pull the sweet spot through the target.
Now kukri tips are generally sharp (although not hardened), but there's no particular reason for the tip to be sharp. We can argue that some swords have rounded tips because the tip is used to pull the sweet spot through, not to cut or stab. This could be proved defnitively by checking for differential hardening. If part of the edge (the sweet spot) is hardened, but the tip is not, then the smith designed it like a kukri.
Best,
F