1) The splash page is incorrect. You only have to beat the boss 30 times to receive the Ancestral Blade
2) Yes your health replenishes at a rate of 1 point per minute. To maximise your hits do the following:
When you've got a full energy bar hit the boss three times and this will leave you with 25 health. Wait 2 minutes for it to go up to 27 health and then you can hit the boss another 2 times. You then have to wait 25 minutes to be able to fight the boss again but if you wait 27 minutes then you can hit twice again when it allows you back into the fight screen.
By using this tactic you can hit a boss 13 times.
Good luck