I get confused everytime I use which or that and refer to someone. For example, which one is the correct to say: 'that courage which takes him up' or should I say 'that courage which take him up'. Appreciate everyone's help.
The word which is referring to the singular noun courage. As it is singular, you would use the conjugation of takes. Don't let the which confuse you - this is used to specify the object that does the action (which in this case is the action of 'taking him up').
The subject of the sentence is courage. You can't have one courage, two courages, et cetera: this kind of word is called uncountable. This concept is used for abstract ideas (courage, fairness), materials (leather, cotton, steel) foods (sugar, cheese) and liquids (water, wine).
Uncountable words are normally treated as singular in sentences, so you use the singular form of the verb:
that courage which takes him up
I say 'normally': if you want to talk about, for example, different types of leather, steel, cheese or wine, you would use the plural- leathers, steels, cheeses, wines. With these, you would have to use the plural form of the verb, for example are rather than is.
In principle, you could also use the word courages to talk about different types of courage, but you would more likely say "types of courage". You would still use the plural form of the verb, because types is plural.