Until recently, I would have assumed the words masorah מסורה / masoret מסורת - "tradition" and musar מוסר - "ethics" all derived from the root מסר - "to hand over, deliver." However, a quick look at Klein's dictionary showed me that I was mistaken.
Here is his entry for masorah:
'Masorah' - the system of notes on the external form of the scriptural text of the Bible. [A secondary form of masoret. The word masoret is probably contracted from ma'asoret מאסרת and is formed with instrumental suffix ma_ from אסר (=to bind). Later, however, the word masorah was explained as the summary of traditions concerning the correct writing and reading of the Bible and, accordingly, was regarded as a derivative of the verb מסר (= to hand down, hand over).]
From the root אסר - "bind, tie, imprison", we also get the words asur אסור - "prohibited", asir אסיר - "prisoner" and isru chag אסרו חג.
Musar, however, has a different source. Klein writes that it originally meant "chastisement, discipline, correction" and derives from the root יסר - "to chasten". This is the root of yisurim יסורים - "suffering, affliction" (only found in the plural). He adds that it is probably related to the root אסר (perhaps prisoners were likely to be disciplined, or those disciplined were likely to be bound).
None of the above are related to the word for the cutting tool "saw" - מסור masor. That derives from the root נסר - "to saw." Both masor and nasar appear in their Biblical form with a sin, not a samech - so in Yeshaya 10:15 we have masor as משור.