Is using a new clean unused sharp leg shving razor bad for your hair ?

I have those disposable Gillette leg shaving razors and i want to use a new unused One to thin the bottom of my hair ... So then will it be bad for my hair ? I intend to do it just once but the razor when u first open it its very sharp and can cut hair easily so it wont tear . So will it be bad if i only do it once ? I want to thin my hair so if its bad for me to use a razor then how can i use my hair cutting scissor to thin the ends of my hair ?