Carrying decent cutlery while flying

You are free to pack these with you in checked luggage (the items have to be sheathed or otherwise covered); the restriction is for carry-on luggage only.

Generally speaking, anything that can be used as a weapon is prohibited on board the aircraft.

In some places, the restrictions are more tough than others. In the US, for example, anything that can be used as or confused with a weapon is not allowed on board.

The TSA only prohibits knives (unless they are rounded or plastic butter knives). They do not have any restrictions on forks and spoons. This covers any airline flying to or from the US.

British Airways specifically prohibits knives longer than 6 cm (see this pdf dated March 2016).

Emirates prohibits "Knives of any kind, type, shape or size" (see this page).

There are no specific guidelines for eating utensils - the guidelines cover safety and security and are concentrated on those things that can be used to threaten or cause harm. As you can see, the rules are different for each airline. So it is best to check with the airline you plan on flying with for specifics.

It is worth mentioning that these rules may be subject to change, so it is recommended that one check before one's itinerary and look out for any specific placards / announcements at the airport.

With regards to alternatives, how about carrying a spork? Some designs such as the Tritensil seem to get good reviews. You might want to look at some comparison sites for reviews, such as this one or this one.

Some more novel types of spork on Amazon:

I often travel with a couple of plastic spoons and forks in my hand luggage, these usually live in my hand bag and nobody ever noticed them when going through security, not even when the contents of the bag was hand searched.
One item that did stand for good use for quite a time was a 'spork' that I got with a baked potato in Newcastle, UK. It did have a bowl like a spoon but with tines into it. So not good for soup but it did work well for many foods.

I mostly re-use good quality spoons and forks I get with take away food, but you can also buy a set in a camping or out-of-doors shop or on internet but you can not see the quality of the material that way.

If you are willing to do with a knife that is just good for pushing your food around, you can aquire one from all of the above sources.
A knife that will cut bread and soft meat should be on sale in a camping shop, get one with a rounded end, so security will not object. It should not be sharp enough to cut through skin.

There are sharp knives available that do not show up on security search machines, but those are often mentioned in the forbidden to take on board lists and might give you problems when found.
It might be best to get a box of cheap 'one use' plastic knives of the most sturdy kind and use those for one time each, have one in your carry-on and a few in your check-in luggage. I am not sure it meets your requirement of durable, it will at least not upset any security guard.

There's been reports of some titanium sporks being taken away by TSA. They say the ones that feature a serrated cutting edge are the most at risk of being confiscated, even though 90% of the time they will let you carry it on. If you want to be 100% sure, try to find a utensil without a dedicated cutting edge, and you should be all good.