**So It is okay to use the models for commercial use, but only if I credited Bungie?
**No.  Do you have any idea how much work goes into making a model?  There are many in the modelling community (myself included) that feel they have a right to monetary compensation for their hard work.  To turn your own phrase.....you'd be "gypping" him of his compensation.  And, you just admitted that you actually wanted to use them commercially.

Learn to model.  Make your own.  Noobness does not last forever.  There are a number of good free modelling programs you could get started with.