Rainer

Rainer (RAY-ner) is an Old German boy name and patronymic surname meaning "deciding warrior," or "advising army." You might choose the older spelling option Rayner, older still is Ragnar, which ultimately came from the elements ragina, "counsel from the gods," and harjaz, "army." It has seen several variations of spelling from country to country, such as Raynor, Rainiero, and Rainier. There's loads of namesakes for each international version of the name, from Prince Rainier of Monaco to the poet Rainer Maria Rilke. Rain is the Estonian short form, but would obviously work well as a nickname today.