Vestri teaches scout skills at the Scout Guild in Blue Mountains.

A dwarf trains scouts in the arts of stealth.
>examine Vestri
He is a thin, sneaky-looking dwarf. He seems willing to
teach you many of the skills dwarven battle-scouts must
master - sneaking, hiding, escaping, and the like.

Skill list

Skill	Sessions	Difficulty
attack	3	Normal
dodge	6	Hard
escape	4	Normal
hide	3	Normal
pick	16	Normal
piercing weapons	4	Normal
search	4	Normal
sneak	3	Hard