What effect does burning the tip have on a striker?
It changes the density of the wood through flame treating (hardening it). It's not necessary honestly. If you like the sound that your striker makes then don't burn the tip- if you don't like it, give it a shot. It will change the pitch that you get.
If you burn the tip over & over you will also start to shorten your striker over time more so than just sanding/conditioning.