This patch is meant to make the game a bit easier and less frustrating. 
Applying this patch to Mega Man 3 will make the weapon energy of all weapons restore fully whenever a life is lost. 
This is done in Mega Man games for the PS1 or later. 
There is a lot of situations in which this could be handy:

- Losing to a boss after exhausting all the weapon energy for the weapon you wanted to use
- Exhausting the weapon energy of the three mobility items, trying to get past a part where it’s mandatory (Needle & Gemini Doc Robot stage)