I would consider pulling out the orchid from the container it is in, just to check exactly the condition of the roots below and the media it came with. The leaf damage could be a combination of mechanical damage during handling and careless watering wherever it was before. You may try and cut off up to point there is a bad part on that leaf, or just cut off the entire leaf. Since we do not know how long that plant has been in bloom, do not be surprised if some blooms start to fade. Either it is just time, or the plant is still acclimating to your home environment.
Personally, I do not spritz on the leaves of my Phals. I try to avoid that, but I do water thoroughly the root zone, with greater intervals during cold season. I also run the ceiling fan to help in overall ventilation around the plant. I try not to get water on the crown of the plant, that is oftentimes how this plant dies, getting too wet there, not drying up and crown rot sets in. During summertime, when it is just too hot and dry here, I dunk the root zone, and my intervals of watering is lesser, sometimes every 3 or 4 days vs. 7 days interval during winter. So you have to adjust your watering regimen as the seasons change. At times too, collar rot happens, that is rotting happening at the base of the plant to just where the roots and leaves connect, maybe due to the plant being too wet there, so it is important for this plant to get good ventilation.
Phals love making aerial roots, and I just let them be. It is just for our convenience that these roots are inside containers, in nature they are found hanging on trees. Eventually that plant will try to grow more to the edge..it likes it that way.
As the blooms die off, the spike may remain green. Some would let it be, and sometimes Phals will rebloom on an old spike. If it starts to yellow, just cut it off, that will allow the plant to redirect its energy to producing more roots and foliage. It will go to a rest mode of sorts, so it seems the plant is doing nothing. But it is just gathering up more energy. Dilute to half recommended the fertilizer you will use; some would do it weakly weekly, some at whatever pace they want..whichever way you choose, make sure you wet the media first before you apply the fertilizer solution. Typically in my area, Phals start to do its next flower spike during late Fall to early Spring.
Enjoy your Phal! Oh btw, there are lots of choices for media..some are comfortable with sphagnum moss...personally I hate that for my Phals..some would use orchid bark mix, some uses lava rock, some would just mount the plant. Whichever one you choose or method you follow...keep the root zone well draining, well aerated.
