Arcana Coelestia # 10101
10101. 'And to fill their hand in them' means a representative sign of Divine Truth emanating from the Lord's Divine Good in the heavens. This is clear from the meaning of 'filling the hand' as consecration to represent Divine Truth emanating from the Lord's Divine Good, and the transmission and the reception of that Truth in the heavens, dealt with in 10019, at this point by those on the lowest levels there.
Arcana Coelestia # 9639
9639. 'Acting in combination with each other' means the consequent joining together of the Lord with those who are in that heaven. This is clear from the meaning of 'acting in combination', when it refers to the power meant by 'the hands', as a joining together effected through truth from good, thus a joining involving those in that heaven. For all in heaven are called 'powers', indeed they are powers by virtue of being recipients of Divine Truth that comes from the Lord. This also explains why God's truths are meant in the Word by 'angels', 8192. Divine Good emanating from the Lord is what joins together all who are in heaven; for that which reigns universally in Divine Truths is Divine Good, and what reigns universally joins people together. This joining together is what the combined action of the hands of a board, of each with the other, means.