kitchen scissors have worked just fine for me but I'm thinking of investing in a pair of longer arm ones as it is sure hard to reach all the way to the back bottom of my new tank.
I use manicure scissors like you pictured above. The curved tip helps me cut only what needs to be cut, especially helpful for removing sword leaves, etc.
Haha! I was going to go that route, but since terresterial plants grow better if they get pruned with sharp, clean cuts as opposed to getting crushed and torn....I figured the same would be true for aquatics.
Why they recommend that you prune you roses and other plants with a sharp edge has more to do with water conservation than damaged to the plant tissue. When you prune a terrestrial plant the sap runs out of the phloem and xylem. This sap then drys and forms a barrier to protect against infection (just like a scab on your arm from a a scratch). A nice clean cut has very little surface area for the plant to scab over. This makes for a quicker heal time and less chance of infection.
In aquatic plants this scabbing process generally does not occur on the wound site. The phloem just dumps the sap directly into the surrounding water until it is stopped. To prevent the loss of photosynthates and nutrients that it has worked so hard to colletec it stops the flow at the nearest node. The portion of the plant between the node and the break/cut generally dies. Many terrestrial plants do this as well (mainly herbaceous ones).
So the key with pruning all plants is to pay attention to where the node is. This is where the meristems are located for the new growth to come from. However using your fingers versus a sharp edge is of little importance to aquatic plants. It's all personal preference.