Why are archdeacons (Anglican, Catholic, or Orthodox) called "The Venerable"? What is the origin, in Latin and English, of this title? Wikipedia doesn't seem to provide a fleshed-out etymology of this title. Who first held it? When did its usage become applied to all archdeacons. And do archdeacons ever have issues with the title, which doesn't necessarily indicate their priestly/diaconal status?
Why are archdeacons (Anglican, Catholic, or Orthodox) called “The Venerable”? What is the origin, in Latin and English, of this title?

I have yet to find a source where where Catholic or Orthodox archdeacons are addressed as “Venerable”.

This is a Iliad address used in the Anglican Church for certain archdeacons and priests. 

An archdeacon historically was the incumbent of an ecclesiastical office dating back to antiquity and up to the fifteenth century of great importance in diocesan administration, particularly in the West. 

First a little history on the subject of archdeacons:


  The term "archdeacon" appears for the first time in Optatus of Mileve's history of Donatism of about 370, in which he applies it to someone who lived at the beginning of that century. From the office of the diaconus episcopi, a deacon whom the bishop selected to administer the church's finances under the bishop's personal direction, the office of archdeacon gradually developed, as certain functions were reserved to him by law. These functions included not only financial administration but also the discipline of the clergy, and examination of candidates for priesthood. From the 8th century, there was in the West a further development of the authority of the archdeacon, who now enjoyed a jurisdiction independent of the bishop.
  
  Large dioceses had several archdeaconries, in each of which the archdeacon (usually by now a priest), had an authority comparable to that of the bishop. He was often appointed not by the bishop but by the cathedral chapter or the king. However, from the 13th century, efforts were made to limit their authority. This was effected in part by the institution of the new office of vicar general. In 1553, the Council of Trent removed entirely the independent powers of archdeacons. Those who had been in charge of different parts of the diocese gradually ceased to be appointed. Only the archdeacon associated with the cathedral chapter continued to exist as an empty title, with duties almost entirely limited to liturgical functions.
  
  The title of archdeacon is still conferred on a canon of various cathedral chapters, and the word "archdeacon" has been defined in relation to the Latin Catholic Church as "a title of honour conferred only on a member of a cathedral chapter". - Archdeacon


The Catholic Church no longer employs the title of archdeacons anymore, but the Orthodox Church still has archdeacons.

Archdeacons are commonly named and addressed a Venerable in the Anglican Community. This address stems for the authority and respect that the faithful have in regards to other priests and deacons.


  Archdeacons serve the church within a diocese by taking particular responsibility for buildings, including church buildings, the welfare of clergy and their families and the implementation of diocesan policy for the sake of the Gospel within an archdeaconry. An archdeaconry is a territorial division of a diocese; these vary in number according to the size of the diocese and in a few cases an assistant bishop in a diocese will also fulfil the duties of an archdeacon in part of it, as in the Archdeaconry of Bodmin 1953–62 (the Archdeaconry of Bodmin is one of two archdeaconries in the Diocese of Truro). Recently, this type of dual role has only existed in the Bishop suffragan(-Archdeacon) of Ludlow.
  
  An archdeacon is usually styled The Venerable instead of the usual clerical style of The Reverend. In the Church of England the position of an archdeacon can only be held by a priest who has been ordained for at least six years. (This rule was introduced in 1840; the requirement that an archdeacon be in priest's orders was enacted in 1662.) In the Church of England, the legal act by which a priest becomes an archdeacon is called a collation. If that archdeaconry is annexed to a canonry of the cathedral, the archdeacon will also be installed (placed in a stall) at that cathedral.
  
  In some other Anglican churches archdeacons can be deacons instead of priests; such archdeacons often work with the bishop to help with deacons' assignments to congregations and assist the bishop at ordinations and other diocesan liturgies. The Anglican ordinal presupposes that the functions of archdeacons include those of examining candidates for ordination and then presenting them to the ordaining bishop. In some parts of the Anglican Communion where women cannot be consecrated as bishops, the position of archdeacon is effectively the most senior office a female cleric can hold: this being the current situation, for example, in the Anglican Diocese of Sydney. - Archdeacon (Wikipedia)


The term venerable seems to stem from England during the 16th century. No title of venerable in reference to an archdeacon can be found in England prior to the reformation.