My thoughts are that "spruce" in this context is playing on the tree motif while referring to the lawyer as cunning and deceitful, as ketchdana said above: deceit, pretence, and bragging.

If someone in Oz describes you as looking "spruce" you need to look carefully at their facial expressions etc to see if they are being nice, nasty or just being wickedly funny.

It reminds me of the word cunning - adjective or noun which originally meant "skillful" or "knowledgeable":

cunning (adj.)

early 14c., conning, "learned, skillful, possessing knowledge," present participle of connen, cunnen "to know," from Old English cunnan (see can (v.1)), from PIE root *gno- "to know." Also compare cun (v.). Sense of "skillfully deceitful, characterized by crafty ingenuity" is probably by late 14c. Related: Cunningly.

cunning (n.)

c. 1300, conninge, "knowledge, understanding, information, learning," a sense now obsolete, verbal noun from connen, cunnen "to have ability or capacity," from Old English cunnan (see can v.1). By mid-14c. as "ability to understand, intelligence; wisdom, prudence;" sense of "cleverness, shrewdness, practical skill in a secret or crafty manner" is by late 14c.

It reminds me of an incident when I was serving an elderly library customer who had a strong Scottish accent. She wasn't happy with the policy I was explaining to her and thought that if she kept talking at me I would waive the policy just for her. She finally said, when she realised that she had lost the argument, that I was very "smart" which in the first nanosecond could be seen as a compliment until I quickly realised that she looked like she was about to jump the counter and bite my head off, literally. I think the word to her meant that I had "outsmarted" her and she was not happy about that at all.