PS: [@Rune_Alchemist]

The bullets Yasha used right now are just effective as an area denial attack. While the initial damage they cause is pretty insignificant, it is quite constant. While it may be strong enough to kill normal and medium level undead/demons/etc , and even take out a good chunk of higher level ones, against Senna, it will be simply annoying, unable to take out even 1/3 of her hp.

Maybe the only thing she will feel is pain, or some debuffs thanks to the shells creating a 'holy' field of some sorts.
Although they are simply targeted to explode above Senna, so she can simply walk away from the affected area (which is quite substantial btw. Not huge, but not tiny either.)