Note that I do not know much about Sikh name origins to know if Jaswinder is indeed derived from Sanskrit yashas + indra, but assuming it is:
There are often no exact translations between words from different languages, or even from the same language but different times. Foremost and Lord are both translations of the original indra, which, comes from the root ind, to drop (as in water drop; related to ud/und, to flow, cognate to the root for water), with an old instrumentative: `that which is used to make drop'. Well, pretty much the only use of this word that survived into the Vedic period, some four thousand or so years back, was as the name of the lord of thunder who used to break asunder mountains of clouds and irrigate the fields and helped recover bovine clouds stolen by the demons. He displaced in the recently agricultural people's minds the former principle deity, varuna, the one that covers, cognate with Uranos, and was thought of as the chief or king of gods. In fact, the root ind was then reinterpretated to mean to lord or to be powerful, and words from the root inv which meant to advance upon was seen as related. And, then one gets indra attached to all kinds of stuff to mean the foremost amongst: gajendra means the biggest amongst the elephants, etc.
yasha, the first element, meant beauty, splendour and worth in the oldest language, but soon took on the meanings of honour, glory, fame, etc. As an adjective, it meant one worthy of those things, beautiful, excellent, worthy, respected, venerated, pleasant, etc. Virtuous could, in some contexts, be a valid translation of this.