I think the artist emphasized Tewi's left hand (money) to distract us from finding what's most precious to Tewi; on Tewi's right, giving Reisen's hand a small window space in the picture to create the aforementioned effect is pretty clever of the artist.
Tewi's right hand is holding on to Reisen. If it's not money she likes, then perhaps (?) Just a thought.
The thing that I find to be the most precious?Isn't it obvious?