das Weh – “sorrow, grief, woe – especially psychological/emotional/mental pain;” elevated style (gehoben)
weh – “sore (painful)”
Most of the words that can be formed using Weh are concrete indicators of where it hurts, but there are two that I like a lot that indicate a different sort of pain: das Heimweh – “homesickness” or “nostalgia” and das Fernweh – “wanderlust.” I was intrigued to see that one discussion on dict.cc suggests that these two words opposites. I hadn’t really thought of them that in way before but it makes sense, perhaps even more so because of Weh connection?!
Where weh appears most often though is in the verb weh tun – “to hurt.” It is one of a family of rather tricky verbs where you are required to use the dative case (if you remember English grammar lessons, this is something like the indirect object). This means the personal pronoun ich becomes mir, du becomes dir, er becomes ihm, and so on, for verbs in this category. This results in constructions that seem very natural to native speakers of German and rather odd to those of us coming to the language from English:
Mir tun die Füße weh – “my feet are aching”
Mir tut alles weh – ‘I’m sore all over”
Both of these throw me off but the second is much more challenging as in the translation “I” is the subject (nominative case) but in German it is rendered as mir (dative case – “me” – which is also the accusative form or direct object form in English).
Often in idiomatic constructions that require the dative, translations include a “to” or a “for” such as Das ist mir unmöglich – That’s impossible (for) me – or Das ist mir besonders interessant – “That’s especially interesting (to) me” – or Es fällt mir ein, dass… – “It occurs to me that…” (in this last case, the non-native speaker can run into even more trouble as here the es – it – is optional). Knowing this fact about the translation is a bit of a double-edged sword, however. It makes using the dative feel a bit better as in English prepositions do have objects, but it means that if you are translating in your head before you speak, you may add an unnecessary preposition to go with that mir. And if you were to choose für to represent that “for,” you may sink even deeper into the mire because für requires an accusative object rather than a dative object which for “I” is mich!
I hope your head isn’t aching too much, if so tut mir leid!