In RP English, the 'w' in "sword" is silent. Wiktionary suggests /sɔːd/ and /soʊrd/.
Why? Are there other words like this? The 'w' is pronounced in words like "swollen", "swoop", "sworn" and "swore".
Learn English – Why is the ‘w’ silent in “sword”
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Best Answer
I have actually heard someone pronounce the /w/, and not facetiously. It must be rather rare, though, and I might say it's a hypercorrection. In any case, my guess is that [wɔ] and [wo] have a tendency to become [ɔː] and [oʊ] in the neighbourhood of consonants such as [s] that don't change much in the presence of labialisation. The matter is complicated a bit by the spread of non-rhotic accents.
The original word was /sweord/, which according to the usual Old English reconstructed pronunciation would be [sweort] or [sweʊrt]. I imagine [eʊ] dropped to [əʊ] or [əu], which is an allophone of [o]. By this time the [w] had become vestigial and was ultimately dropped, but English spelling is far more conservative than its pronunciation, so the /w/ was retained.