A key work is untranslated in this verse, leaving us exactly the wrong impression. This verse is the punchline to Jesus response to the Apostle's request to increase their faith, explaining why the Apostles cannot command a tree to uproot itself.  In this analogy, the apostles and the tree are the bondsman due to serve, not command.  The KJV translated seems odd because those doing what they are commanded to seem to be calling themselves "worthless servants" (see meaning in Matthew 25:30). However, this misses the point of the verse.  not that we are worthless despite doing what we are suppose to do, but we do what we serve and do not command because we are worthless servants.

The word translated in KJV as "so" is in its adverbial form, so it means "in this manner" or "in this way."

The Greek word translated as "likewise" is used as the conjunction "and", but it also is used to add emphasis ("also").

The pronoun "ye" is used explicitly as the subject of the sentence. Since it is already part of the verb, its use here creates emphasis on the "you" as we might say "you yourselves." It is plural.

The Greek word translated as "when" introduces a phrase that explains a certain condition so "whenever" or "since."

The Greek word translated as "ye shall have done" has the primary meaning of "making" or producing" something or "causing" or "performing" as service. It describes a productive action.  It is not as broad a word as the English "do", which covers all actions, productive or not. The form is most like that of a possible action performed at any time, past present or future, "you might perform".

The word translated as "all" is the Greek adjective meaning "all", "the whole", "every," and similar ideas. When it is used as a noun, we would say "everything." As an adverb, it means "in every way", "on every side," and "altogether."

The word translated as "the things that" is the Greek definite article, which usually precedes a noun and, without a noun, takes the meaning of "the one." The Greek article is much closer to our demonstrative pronouns ("this", "that", "these", "those"). See this article for more. 

"Were commanded" is from a Greek verb used for the first time bu Jesus here. It  means to "appoint", "ordain", "dispose"", arrange for oneself", "classify", and, in the passive, " to be appointed". It is in the passive. Again, the tense is not the past, but a form that means at any time. So the sense here is "those ones" or "these things".

The Greek pronoun "you" here is plural and in the form of an indirect object, "to you", "for you", etc. This is no the "you" of "you say", as it might appear, but "appointed to you". The "you" that is the subject is the earlier one above.

The word translated as "say" is the most common word that means "to say," and "to speak," but it also means "to teach," which seems to be the way Christ uses it more frequently. It also has many ancillary meanings such as "to count" ("to number" or like we might say, "to recount" a story) or "to choose for yourself." Christ usually uses this word to refer to his own speaking or teaching.

An untranslated word appears here that introduces a statement of fact or cause, "in order that", "because", or "since".  This missing word makes sense out of the verse, it introduced the clause that explains why we do what we are commanded by our Master.

The verb "we are" here is the common form of "to be" in Greek. It means to have a certain characteristic or remain in a certain condition. It also equates terms or assigns characteristics. This word appears at the end of the phrase, not the beginning.

"Unprofitable" is from a word Christ uses rarely that means means "useless" and "worthless". This word follows the "servants" clarifying it. This is part of Jesus's humorous style.

The noun translated as "servant" means "slave" or "bondsman".  It is translated as "servant" to update the Bible.

The Greek word translated as "we have done " has the primary meaning of "making" or producing" something or "causing" or "rendering" as service. It describes a productive action.  It is not as broad a word as the English "do", which covers all actions, productive or not. 

The word translated as "that which" is a demonstrative pronoun ("this" "that"), but it often acts as a pronoun ("the one that), especially a connective pronoun ("the one that") introducing a dependent clause.

"Was our duty " is from a Greek verb that means "to owe", "to have to pay," "to be bound", and "to account for."  It is not a passive form as translated, but a first person form, "we were bound". "

The Greek word translated as "to do" has the primary meaning of "making" or producing" something or "causing" or "performing" as service. It describes a productive action.  It is not as broad a word as the English "do", which covers all actions, productive or not. The form is correct, an infinitive, "to perform."