The quaich is often referred to as 'the loving cup' or cup of welcome or friendship and its two handles make it ideal for sharing.
It is unique to Scotland and part of the tradition of Celtic hospitality was that of welcoming guests with a drink from a quaich. Sharing a cup was also seen as a sign of trust between the people drinking from it - because it is offered and taken with both hands, the drinker could not hold a weapon at the same time and the sharing of the drink was also a guarantee that it hadn't been poisoned!
King James VI of Scotland presented a quaich to Anne of Denmark on the occasion of their marriage in 1589 and since then quaichs have often been used in wedding ceremonies. Drinking from the same cup is a lovely symbol of the love and trust between the couple. Because it is traditionally 'the cup of welcome', drinking from it can also be seen as a way of welcoming the bride and groom into each others' family too.
There are lots of ideas for incorporating a quaich into your ceremony: