looks like something fairly generic, mass produced for cheap cost. You might see this under "frost cutlery" name or on HSN TV where 40 knives sells for $40.  uses low-end steel to produce a product limited to a strict price point.
I would use it for open envelopes, very light cutting duty like paper or plastic bag.  Basically anything you can do with a slipjoint, you can do with this one, pretend it doesn't have a lock.  Without further knowledge, I wold not trust the lock too much simply because it was built to a price point.