I do believe that the pastor I was speaking to thinks that deacons do not have authority, as they are actually carrying out the will of the session, or serving on behalf of the session, maybe? I am not sure, and I don't want to misquote him, but I got that feeling, so women deaconesses wouldn't be an issue of authority. (I do not know whether all of this was devil's advocate or stemmed from personal opinion, as it came about in a discussion between us and not me interviewing him!)
Clearly, the doctrine of Scripture reflected by our Book of Church Order is that the church is governed by Deacons and Elders. Both are authoritative, leadership offices reflecting the explicit qualifications of Scripture that they be men (I Timothy 3, Titus 1).
Deacon is not merely a synonym word for servant. The same word for deacon (servant) sometimes describes Christ ministering. Hopefully, no one would dare represent Christ was only a servant, had no authority, no special title, etc.
The office of Deacon is a leadership one, reflecting not only the explicit qualification of Scripture, but the creation order. In the PCA, the spiritual charge, all leadership roles are:
1) oversee mercy ministry
2) oversee property stewardship
3) develop a spirit of liberality in the congregation
Off-and-on in church history there were "deaconesses" but they were patterned after I Timothy 5 (60 year old widow, vows to remain unmarried, destitute, and financially dependent on the church). There were times in church history the church deviated from those qualifications (e.g. lowered the age to 40) and got into all kinds of trouble. Younger women broke their vows to remain unmarried, left church service primarily, etc. So the practice fell into disuse. It was abandoned.
Only since about 1960, in all of church history, with the liberalism/modernism has it been promoted that I Timothy 3 was an interchangeable office men and women.
More-and-more, what is becoming clear that what is at stake is the office of deacon itself- a high office, qualified, elected, ordained and installed- a perpetual office with high spiritual reward.
By arguing it is only a substitute word for servant only we devalue it, misunderstand it, and trivialize it. When we "commission" but not ordain we devalue the holy ordinance of ordination. What's happening, it appears is that polity and the doctrines of ordinance and church governance are not being taught by some from the pulpit. That's part of their vows, but they are not doing it, and that is causing confusion.
One of the best research papers on the biblical issues and church history on this is Brian Schwerley's
http://www.all-of-grace.org/pub/schwertley/deacon.html