"I want new shoes."

Translation: Dw i eisiau esgidiau newydd.

[Rumactree]

Remind me why we don't say "dw i'n eisiau ..."? I see that we don't but I don't know why - are there other verbs that do and don't like an yn? Or is there a meanin I'm missing? Any informed thoughts appreciated.

[rmcode]

'Eisiau' is really the noun for 'wanting'. Traditionally the expression 'I want' in Welsh was 'Mae eisiau arna i' = 'There is wanting on me'.

This is quite a cumbersome sentence and in the modern world has changed to follow the normal pattern for simple sentences, but because of its origins the expression doesn't use 'yn'.

There are very few other similar examples of this and so be reassured you need 'yn' or 'n in normal sentences using verbs.

[Rumactree]

Thank you, that helps.
Just curious here with how you use it: So my Nain might have said "Mae eisiau esgidiau newydd arna i"?

[rmcode]

Yes, very likely.

[ibisc]

There is a detailed explanation here