Are there any online etymological dictionaries of Mandarin (not for characters but for spoken words)
The ABC Etymological Dictionary of Old Chinese is searchable online here:

http://edoc.uchicago.edu/edoc2013/digitaledoc_index.php

Go to 'EDOC: Linear Output', select 'All' on the right-hand side (under 'ABC Etymological Dictionary of Old Chinese'), type in your characters, and click 'Display Phonetics'.  For more complicated searches, go to 'EDOC: Search'.

Also, to give a simple example to help clarify what the OP is referring to as "character etymologies" vs. "word etymologies", the ABC dictionary gives the following for 蜜 (mì):


  ‘Honey’ [Chuci]. || [T] MTang mir &lt; mir, ONW miit — [D] PMin *mit || [E]
  Thought to be borrowed from IE-Tocharian B mit ‘honey’ &lt; PTokharian *mjət
  (Behr Oriens 1999 / 2000: 36).


The above is a word etymology.  It is a loanword, of Indo-European origin, and is in fact related to English "mead", Lithuanian "medus", Greek "μέθη", Russian "мёд", and Farsi "می", for example.

A character etymology would decompose this character into 虫 (insect radical) and 宓 (phonetic), which is in turn decomposed into 宀 (roof radical) and 必 (phonetic). Both 虫 and 宀 can be traced back to the oracle bone script, while 必 can be traced back to the bronzeware script. (Source: hanziyuan.net)

The character and word etymologies are quite distinct - while all of the components of the character are of Chinese origin, the word itself is Indo-European.