_the_, the definite article particularizing the noun man.

_old_, an adjective, positive degree, qualifying the noun man.

_man_, a common noun, 3rd person singular, masculine gender, objective
case governed by the transitive verb _see_.

_coming_, the present or imperfect participle of the verb "to come"
referring to the noun man.

_but_, a conjunction.

_alas_, an interjection, expressing pity or sorrow.

_he_, a personal pronoun, 3rd person singular, masculine gender,
nominative case, subject of verb has walked.

_has walked_, a regular, intransitive verb, indicative mood, perfect tense,
3rd person singular to agree with its nominative or subject _he_.

_with_, a preposition, governing the noun difficulty.

_much_, an adjective, positive degree, qualifying the noun difficulty.

_difficulty_, a common noun, 3rd person singular, neuter gender,
objective case governed by the preposition _with_.

N.B.--_Much_ is generally an adverb. As an adjective it is thus compared: