Currenty the cheapest way to get something to fuse is to the level 1 legs or level 1 weapons. However, it takes quite a long time until I fused enough items into my level 11 weapon (not to mention my level 18 torso) until I gain on level.

Has anyone found a workaround for this dull clicking? It also seems that there is hardly any use to increase the level beyond 4, as both prices and time consumed are too high.

Doesn't seem to be it took me and hour and a half to buy and then fuse level 1 legs, to get my torso level from level 6 to level 7. Best way I've found of doing it is after every game, spend money on level 1 legs and fuse them straight away. You can buy about 20 level 1 legs after a win, so it only takes 2 minutes to buy and fuse them to an item and it doesn't feel as tedious because you still get to fight often