Interpreter's oath/Dolmetschereid

Here's a curious question from an ITI member. This is the interpreter's oath, which is taken by all interpreters in courts in England: I swear by Almighty God that I will well and faithfully interpret and make true explanation of all such matters and things as shall be required of me according to the best of my skill and understanding. Gosh - haven't they modernized that one? The colleague thinks that 'to the best of my skill' is wrong and should be 'to the best of my skills', because 'best' is a superlative adjective and it implies comparison between at least two objects (actually, as a superlative, it would have to be three, because 'better' applies to two). He actually wants it changed. I can't see this at all. I am familiar with the legalese expression 'to the best of my knowledge' and 'to the best of my ability'. These are uncountables, as are 'skill' and 'understanding' in the oath. 'Skill' can be countable too - a good source for information on countable and uncountable meanings is the Longman Dictionary of Contemporary English, which is now online. Now if 'skill' should be plural, then 'understanding' must be wrong too - which it isn't! I think both 'to the best of my skill' and 'to the best of my skills' are correct English. However, although I find 27,000 ghits for the plural, I only find seven of them on UK sites. So if you are in Canada or India or the USA, 'skills' is OK here. Most interpreters in Germany swear an oath when they are appointed, so they don't have to swear in court. I did manage to affirm when I became a court-certified translator, although the courts seem fairly unfamiliar with that procedure here. In…