Swordplants (Echinodorus sp.) are different from stem plants so "trimming" is not going to affect height much, if at all. Sometimes the plant may remain shorter if leaves are continually removed; this has the effect of telling the plant that something is wrong, so it changes its growing tactic.
If leaves are removed, they should only be the outer older leaves. New growth is from the centre of the crown. Removing old leaves is optional, but sometimes this can hamper the plant nutrients. Some nutrients are mobile, which means that the plant can move them from older leaves to new growth. This obviously keeps the plant stronger, preventing stunted new growth, especially if some nutrients may not be as available in the water. Over fertilizing can increase algae issues, so you do not want to be using more fertilizers than necessary, and here the plant can help you.
I tend to remove the older outer leaves if they begin yellowing, and have begun rotting through at the base which when completed means the plant can no longer move nutrients up or down the stem, so there is obviously no point retaining this leaf. By this stage it is usually pretty obvious, and yellowing edges will generally be noticeable. I sometimes give a gentle tug on the leaf, and if it remains attached, it is still viable.
As for the hatchetfish, they appreciate some leaves at the surface, or just under/just above. Provided the surface is not blocked completely, they will be very happy and less stressed. The sword in the photo is no where near being an issue.
Having said all that, some of the older outer leaves do seem to be dying, so these I would probably remove. Give them a gentle tug (grab the leaf stem just below the leaf blade, otherwise pulling the leaf might break it and you may not want to remove it) and if it easily comes off the crown, and appears brownish instead of white at the base, it was dying.
Byron.