"obstacles at hand" is a correct and usable phrase in written English.
For example, you might say, "We must find solutions to the obstacles at hand if we are to succeed."
If he could speak to us today, he would ask us to remember him not by mourning what might have been, but by looking clearly at the opportunities and obstacles to peace and getting on with the work at hand.
In fairness, the obstacles are many: incompetency, corruption, the sheer complexity of disbursing huge sums, the multiplicity and difficulty of the tasks at hand — defense, education, health, prisons, courts, police, disaster relief, regulation of markets, banks, drugs, food safety.
Instead of getting upset, feeling hopeless and giving up in the face of obstacles, they take the opportunity to put on their thinking caps and come up with a creative solution to the problem at hand.
An obstacle to the use of biomimetics in engineering is knowledge of biological phenomena that are relevant to the problem at hand.
There are weapons at hand.
