The strap should hold fine as it appears to be an Atwood boat ladder assist handle rated above 250 pounds.
If the whole area under the weights has Velcro it should hold up for a good amount of time if taken care of and care is taken to make sure all,Velcro is seated or mated well before a lift takes place.
Are you sure it is there to be an assist handle or is it there just to transport the weights?