What does Walter mean?
From Germanic 'wald' (rule, power) and 'heri' (army), giving 'ruler/commander of the army'. Brought to England by the Normans.
What does Louis mean?
From the Frankish Hludwig, combining 'hlud' (famous, loud) with 'wig' (war, battle), hence 'famous in war'. Carried by 18 kings of France.