Joshua noticed that even just maintaining his connection with the barrier bubble drained his mana at incredible speed. But he could understand why. Joshua could sense everything inside the bubble. It was hard for him to maintain the connection due to the influx of overwhelming amounts of information, but he managed to ignore most of it and only focus on what he needed to. The barrier and the mana.
It would be impossible for him to sustain his connection with the barrier much longer with only his own mana, much less change it so he could help Lucy. Joshua remembered how he had almost drowned in mana when he trained training after accidentally making a subconscious connection with the barrier.
